In pitest mutations are seeded into your code, then your tests are run. The assumption is: If your unit test don't fail after changed code, it may indicate an issue with the test suite.

In fuzz testing, the mutations are seeded into the inputs. Depending on the fuzzing approach, those might be seeded from random, patterns, application behavior, etc. Jazzer is based on libFuzzer, meaning that it's feedback-loop is based on which coverage metrics are reported during run-time.

Integrating important JVM projects is work in progress ;-)