Java: What is the difference between Spring Boot and Spring Framework?

Spring Framework — the core IoC container and dependency injection framework. Spring Boot — an opinionated layer on top of Spring that simplifies setup with auto-configuration, embedded servers, and starter dependencies.

Spring Boot advantages:

• Auto-configuration — configures beans based on classpath.
• Embedded servers — Tomcat, Jetty, Netty included.
• Production-ready features — Actuator, metrics, health checks.
• Starter dependencies — simplified dependency management.

1// Spring Boot application
2@SpringBootApplication // Combines: @Configuration + @EnableAutoConfiguration + @ComponentScan
3public class MyApp {
4    public static void main(String[] args) {
5        SpringApplication.run(MyApp.class, args);
6    }
7}
8
9@RestController
10class HelloController {
11    @GetMapping("/hello")
12    String hello() {
13        return "Hello, World!";
14    }
15}
16
17// application.yml
18server:
19  port: 8080
20spring:
21  datasource:
22    url: jdbc:postgresql://localhost/mydb
23  jpa:
24    hibernate:
25      ddl-auto: update

Key differences:

• Boot = Framework + defaults + tools.
• Boot has starters; Framework needs manual config.
• Boot has embedded server; Framework needs external deployment.
• Boot has Actuator; Framework needs custom monitoring.