Comparisons
Spring vs Spring Boot: What's the Difference?
This is less a "which to choose" comparison and more "what does Spring Boot actually add on top of Spring" -- a very common interview question.
Side-by-Side Comparison
| Spring Framework | Spring Boot |
|---|---|
| Manual bean configuration (XML or Java config) | Auto-configuration based on your classpath |
| Requires a separately installed servlet container | Ships an embedded server -- run with java -jar |
| More setup boilerplate to get a working app | A working REST API from a single @SpringBootApplication class |
| Full control over every configuration detail | Sensible defaults, with full override capability when needed |
Which Should You Use?
For any new project today, Spring Boot -- there's essentially no reason to hand-configure plain Spring from scratch anymore. You're still using Spring Framework underneath either way; Spring Boot is built on top of it, not a replacement for it. The distinction mostly matters for understanding legacy codebases (some older enterprise systems still run on plain Spring configured manually) and for interviews, where explaining the difference clearly is a common question.
Frequently Asked Questions
Yes -- Spring Boot doesn't replace Spring's core concepts (dependency injection, beans, AOP); it removes the manual configuration overhead around them. Understanding core Spring concepts makes Spring Boot's auto-configuration far less mysterious when something doesn't work as expected.
It's rare -- almost every new Java web project starts with Spring Boot today. The main scenario for plain Spring is maintaining or extending an existing legacy codebase that was never migrated to Boot.