What is the difference between SpringJUnit4ClassRunner and SpringRunner

There is no difference, from the javadoc:

SpringRunner is an alias for the SpringJUnit4ClassRunner.

ref: https://docs.spring.io/spring/docs/4.3.0.RC2_to_4.3.0.RELEASE/Spring%20Framework%204.3.0.RELEASE/org/springframework/test/context/junit4/SpringRunner.html