Spring vs Spring Boot vs Spring MVC vs Spring Data: what is each?

Spring Framework: core container (IoC/DI), AOP, transactions and the base of everything.
Spring MVC: the web module: controllers, DispatcherServlet, request mapping, JSON conversion.
Spring Data: simplifies data access (JPA, MongoDB, Redis...) with repository interfaces.
Spring Security: authentication and authorization.
Spring Boot: opinionated layer that auto-configures all of the above, adds starters, embedded server and Actuator.
In one line: Spring is the toolbox, Spring Boot is the pre-assembled workshop.