If you're new to the Spring ecosystem, one of the most common questions you'll ask is:

"What is the difference between Spring and Spring Boot?"

Both frameworks are hugely popular in the Java world, but they serve different purposes. Spring is the foundation. Spring Boot is the accelerator.

This post explains their differences in the simplest and most practical way, so you can understand why Spring Boot exists and when to use it.

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1. What Is Spring?

Spring is a comprehensive, modular Java framework that helps developers build enterprise-grade applications. It provides solutions for:

• Dependency Injection & IoC
• Web MVC
• Data access & JPA
• Security
• AOP
• Messaging
• Testing

However, Spring requires a lot of manual setup:

• Configure dependencies manually
• Configure application servers
• Manage XML or Java configs
• Set up MVC components
• Handle boilerplate for JPA, transactions, etc.

Spring is powerful — but not beginner-friendly.

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2. What Is Spring Boot?

Spring Boot is a layer built on top of Spring designed to remove all the heavy lifting. Its goal is simple:

Make Spring development faster, simpler, and more efficient.

Spring Boot focuses on:

• Zero configuration
• Auto-configuration
• Embedded servers
• Starter dependencies
• Production-ready features (Actuator, metrics, logging)

Think of Spring Boot as:

Spring, but with all the wiring and configuration done for you automatically.

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3. Spring vs Spring Boot: Key Differences

Here's a clean comparison that makes the differences obvious:

Feature	Spring	Spring Boot
Setup	Manual configuration	Auto-configuration
Server	Requires external server (Tomcat/Jetty)	Embedded server included
Dependencies	Select & configure manually	Starter packs (spring-boot-starter-*)
Configuration	XML or Java-based	Almost zero configuration
Speed	Slower development	Rapid development
Project Size	Large configs, multiple files	Minimal, clean, focused
Production Tools	No built-in production features	Actuator, health checks, metrics
Learning Curve	Higher	Much easier

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4. Why Spring Boot Was Introduced

Spring was powerful but becoming too complex.

Developers complained about:

• Managing too many dependencies
• Writing large XML files
• Setting up application servers
• Spending days configuring instead of coding
• Hard-to-manage project structures

Spring Boot solves these challenges by:

• Auto-configuring what you need
• Providing defaults for most cases
• Embedding the server
• Handling dependencies for common use cases
• Giving production-ready features without extra work

Spring Boot accelerates productivity — especially for REST APIs and microservices.

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5. Analogy: Spring vs Spring Boot

Imagine building a house:

Using Spring

You get raw materials:

• Bricks
• Cement
• Pipes
• Wires
• Wood

You must hire workers, plan the structure, and manage everything manually.

Using Spring Boot

You get a pre-built modular home:

• Ready wiring
• Ready plumbing
• Pre-installed cabinets
• Pre-installed appliances

You just move in and start living.

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6. When Should You Use Spring?

Use Spring (without Boot) when:

• You need fine-grained control over configuration
• You are working on legacy applications
• The environment has strict enterprise standards

For new modern apps, pure Spring is less common.

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7. When Should You Use Spring Boot?

Use Spring Boot when you want:

• Fast API development
• Ready-to-use microservices
• Auto-configured JPA, Security, Kafka, etc.
• Easily deployable applications
• Embedded servers (no WAR files)
• Cloud-native applications

Spring Boot is the default choice today for new Java apps.

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8. Summary

Here's the simplest way to remember the difference:

• Spring gives you the building blocks.
• Spring Boot assembles them automatically so you can start building your product faster.

Spring Boot is not a replacement for Spring — it's an extension that makes it incredibly efficient.

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What's Next?

In the next post:

03 - Spring MVC vs Spring Boot: When and Why to Use Each

We'll compare Spring MVC's request-handling model with Spring Boot's auto-configured web framework to understand the evolution of Java web development.