Difference between Spring and Spring Boot
In short
- Spring Boot reduces the need to write a lot of configuration and boilerplate code.
- It has an opinionated view on Spring Platform and third-party libraries so you can get started with minimum effort.
- Easy to create standalone applications with embedded Tomcat/Jetty/Undertow.
- Provides metrics, health checks, and externalized configuration.
You can read more here http://projects.spring.io/spring-boot/
Basically, Spring Boot is an opinionated instance of a Spring application.
Spring Boot is a rapid application development platform. It uses various components of Spring, but has additional niceties like the ability to package your application as a runnable jar, which includes an embedded tomcat (or jetty) server. Additionally, Spring Boot contains a LOT of auto-configuration for you (the opinionated part), where it will pick and choose what to create based on what classes/beans are available or missing.
I would echo their sentiment that if you are going to use Spring I can't think of any reasons to do it without Spring Boot.
Unfortunately and I mean this out of personal frustration with Spring boot, I have yet to see any real quantified list, where the differences are explicitly outlined. There is only qualifications such as the rubbish sentence "...opinionated view..." which are bandied about.
What is clear, is that SpringBoot has wrapped up groups of Spring annotations into its own set of annotations, implicitly. Further obfuscating, and making the need for anyone starting out in SpringBoot to have to commit to memory what a particular SpringBoot annotation represents.
My reply therefore is of no quantifiable benefit to the original question, which is analogous to that of the SpringBoot authors. Those behind Spring IMO deliberately set-out to obfuscate, which reflects the obtuseness of their JavaDoc and API's (see SpringBatch API's as an example, if you think I am flaming) that makes one wonder the value of their open-source ethos.
My quest for figuring out SpringBoot continues.
Update. 22-08-2022
Read this (https://docs.spring.io/spring-boot/docs/current/reference/html/using.html#using.auto-configuration) and you will figure out for yourself what "opinionated" means. There are over 140 Config classes that Springboot can use for this opinionated view, depending on what is on your classpath. yes, on your classpath. Finally and bizzarely, the annotation @SpringBootApplication is a configuration annotation as it includes it. Go figure :=)