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In this article, we organize the differences between Spring and Spring Boot from the perspective of “what gets easier” and “what you have to configure yourself,” explained clearly so that beginners can choose without hesitation.

What is Spring?

Spring is the “foundation (framework)” for building applications in Java. It is especially known for its design centered on DI (Dependency Injection) and IoC (Inversion of Control), which loosens the coupling between classes and makes it easier to write code that is testable and resilient to change.

The term “Spring” is a bit broad, and in practice it usually refers to the “Spring Framework.” The Spring Framework includes many features, such as Spring MVC for web development, Spring JDBC for data access, transaction management, and more.

What is Spring Boot?

Spring Boot is a “mechanism (extension) that lets you get started right away” with Spring-based development.

While the Spring Framework offers a high degree of freedom, it tends to require a lot of upfront work (configuration and dependency adjustments). Spring Boot addresses this by providing common configurations in advance, dramatically reducing tedious initial setup.

The three keywords that come up most often with Spring Boot are:

  • Auto Configuration: Looks at your dependencies and automatically configures what you “probably want”
  • Starter: Lets you pull in a complete set of required libraries at once
  • Embedded Server: Lets you embed Tomcat or similar, so the application can run on its own

The Short Answer

In a nutshell, this is the cleanest way to think about it.

  • Spring: The powerful, highly flexible “framework itself”
  • Spring Boot: A “convenience package” that makes Spring development easier (handles startup, configuration, and dependencies)

Spring Boot is not “something separate from Spring.” The correct way to think of it is “something that sits on top of Spring and improves the development experience.”

Understanding the Differences Through Concrete Examples

First, let’s capture the differences in a single table. You can read the detailed explanations later; the table alone is designed to give you the big picture.

AspectSpring (Spring Framework)Spring Boot
RoleThe framework itself, providing DI, MVC, and moreA development support mechanism that sits on top of the Spring Framework
ConfigurationYou assemble it yourself with Java Config or XMLAuto Configuration looks at your dependencies and configures things automatically
DependenciesYou pick libraries individually and align versions yourselfYou add them in bulk via Starters, and Boot manages the versions
How it runsOften deployed as a WAR to an external Tomcat or similarRuns standalone via java -jar thanks to the embedded server
Externalized configurationYou build the mechanism yourselfCan be overridden from the start via application.properties or environment variables
Best suited forMaintaining existing setups, or when you want to learn the internals deeplyNew development, quick launches, and as an entry point for learning

Note that this article assumes Spring Boot 3.x or later (Spring Framework 6.x or later) and Java 17 or later. Java 17 became mandatory starting with Spring Boot 3.0, and this requirement remains unchanged in Spring Boot 4.0, released in November 2025. If you are running an older combination, be sure to also read the migration section introduced later.

With this table in mind, let’s go through each point with concrete examples.

Below are the points where the differences are easiest to see, ordered by where beginners are most likely to stumble.

The Amount of Configuration Differs

To run Spring MVC without Boot, you write an initializer class yourself that registers the DispatcherServlet, like the following.

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class WebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
  @Override
  protected Class<?>[] getRootConfigClasses() {
    return null;
  }

  @Override
  protected Class<?>[] getServletConfigClasses() {
    return new Class<?>[] { WebConfig.class };
  }

  @Override
  protected String[] getServletMappings() {
    return new String[] { "/" };
  }
}

On top of this, you also need a WebConfig class annotated with @Configuration and @EnableWebMvc, settings for JSON conversion and views, and an external Tomcat prepared as the deployment target. With so many files to touch before anything runs, beginners often get stuck right here.

When building a web application with the Spring Framework alone, the amount of configuration grows depending on the environment (XML or Java Config, server settings, and so on).

With Spring Boot, you can often get things running just by adding a dependency (Starter) and writing minimal configuration. For a web application, for example, this is basically all you need to get started.

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {
  public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
  }
}

@SpringBootApplication is actually a convenient bundle. Roughly speaking, it signals “do component scanning and also enable Spring Boot’s auto configuration.”

How Dependencies Are Added Differs

With Spring Boot, using “Starters” is the norm. For example, if you want to build a Web API, in Maven it looks like this.

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>

This single dependency brings in the typical Web API setup as a package: Spring MVC, embedded Tomcat, JSON conversion, and more. With Spring (without Boot), you more often find yourself picking the required libraries individually and aligning their versions.

How the Application Starts Differs

Thanks to the embedded server, Spring Boot can be “launched as a Java application.”

  • ./mvnw spring-boot:run
  • or java -jar xxx.jar

On the other hand, when using Spring MVC in the traditional way, it is common to deploy a WAR to an external application server (such as Tomcat), which adds a bit more environment preparation.

If your application feels “slow to start” after moving to Spring Boot, we explain how to find the cause and how to shorten startup time in How to Speed Up Spring Boot Application Startup: CDS, AOT, and Lazy Initialization.

Common Misconceptions

If I use Spring Boot, I don’t need to learn Spring?

No. Spring Boot does “hide” some of Spring, but in real-world work, the better you understand Spring’s fundamentals (DI, transactions, Beans, and the configuration mindset), the stronger you will be.

Spring Boot makes things “easier,” but it does not make them “unnecessary.”

Does Spring Boot magically do everything?

Auto configuration is convenient, but treating it as a complete black box makes it easy to get stuck. For example, we recommend gradually learning the roles of application.properties / application.yml so you can trace “which setting is taking effect from where.”

server.port=8081
spring.application.name=demo-app

This design, where the application can be “configured from the outside,” is another reason Spring Boot is so easy to use.

Which Should Beginners Start With?

As a rule, starting with Spring Boot is easier to learn.

  • It runs right away, so it is easy to build early success experiences
  • You can quickly get hands-on with patterns commonly used in the field, such as Web APIs and DB connections
  • Dependencies and startup are simple, so there are fewer obstacles to learning

Then, once you are comfortable, gradually understanding “what auto configuration is doing” will deepen your understanding of Spring as a whole.

Choosing in Practice (By Project Type)

In the field, the decision is usually not “which one to learn” but “which setup to start development with.”
When in doubt, using the following criteria will keep your decisions consistent.

CaseRecommendationReason
Launching a new business API in a short timeframeSpring BootFastest way to build the initial setup and operational foundation
Quickly iterating on small experiments or PoCsSpring BootFewer steps to get running, so validation is fast
Maintaining an existing legacy Spring setupSpring (existing setup)Safer to prioritize consistency with the existing design
Learning with the goal of deeply understanding framework internalsSpring + Spring BootYou can pick up the fundamental concepts while using it

In practice, “choose Spring Boot while deepening your understanding of Spring fundamentals” is the most reliably repeatable approach.

Points to Decide Before Migrating

When migrating from Spring (without Boot) to Spring Boot, deciding the following upfront reduces failures.

  • Pin the Java version and Spring Boot version
  • Unify the policy for managing configuration files (application.yml, environment variables, Secrets)
  • Add logging and monitoring (Actuator, metrics) at an early stage
  • Decide the testing strategy first (unit, integration, startup tests)
  • Template the initial security settings (authentication, CORS, CSRF)

Deciding these at project kickoff, rather than “after it starts up,” keeps operational costs down.

When pinning versions, pay particular attention to the fact that Java 17 is mandatory from Spring Boot 3.x onward, and to the package replacement from javax to jakarta. The concrete steps are summarized in Spring Boot 2.x to 3.x Migration Guide: Java 17 Required, With Checklist. Also, the introduction of Actuator and its exposure settings, which are the first step in monitoring, are explained in Getting Started with Spring Boot Actuator.

Common Judgment Mistakes

Assuming you don’t need to think about design if you use Spring Boot

Spring Boot reduces initial configuration, but it does not reduce design decisions themselves.
Dependencies, exception design, transaction boundaries, and logging policy still need to be designed separately.

Disabling too much auto configuration

Turning off all auto configuration “for the sake of understanding” can actually reduce maintainability.
It is safer to leverage the defaults first and explicitly adjust only the parts you need.

Summary

  • Spring is the foundational framework for Java development
  • Spring Boot is a mechanism that lets you quickly get started with Spring-based development
  • The differences show up in how easy “configuration,” “dependencies,” and “startup” are
  • Beginners will find it easier to learn by starting with Spring Boot

As a next step, we recommend building a simple REST API with Spring Boot and getting familiar with the roles of DI, @RestController, and @Service.

If you want to take your understanding of DI one step further, also see Introduction to Spring @Bean “Names”: When to Set Them, How They Work, and Precedence, which explains how Bean names are determined and which Bean is chosen when multiple Beans of the same type exist.