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

@RunWith(SpringRunner.class) tells JUnit to run using Spring’s testing support. SpringRunner is the new name for SpringJUnit4ClassRunner, it’s just a bit easier on the eye.

SpringRunner is only available on spring-test 4.3.

SpringRunner class extends SpringJUnit4ClassRunner.

Source code of SpringRunner is

package org.springframework.test.context.junit4;

import org.junit.runners.model.InitializationError;

public final class SpringRunner extends SpringJUnit4ClassRunner {

    public SpringRunner(Class<?> clazz) throws InitializationError {
        super(clazz);
    }

}