Spring is an "engine"
Spring MVC is an MVC framework based on Spring
Spring Boot is a rapid development integration package based on Spring4's conditional registration
Spring initially utilizes "factory pattern" (DI) and "proxy pattern" (AOP) to decouple application components. Everyone thinks it's very useful, so according to this model, we built an MVC framework (some components decoupled with Spring), and used it to develop web applications (SpringMVC). Then I found that every time I developed a lot of dependencies, it was very troublesome to write a lot of boilerplate code, so I made some lazy integration packages (starters). This set is Spring Boot.
For decades, Spring's effort has been to reduce complexity, decoupling, and code less. My feeling is that complexity doesn't come out of nowhere and doesn't go away out of nowhere,
Just move from one place to another. Although mastering Spring can reduce a lot of redundant work, mastering Spring itself becomes a very complicated thing.
Spring's XML, annotation configuration, and EL expression DSL complicates many simple things. When Spring Boot's automatic configuration fails, it brings more trouble.