AFLChurn++ is a reimplementation of AFLChurn on AFL++ rather than AFL.
AFLChurn is a regression greybox fuzzer that focusses on code that is changed more recently or more frequently.
AFLChurn was originally developed based on American Fuzzy Lop (AFL) which was originally developed by Michal Zalewski.
AFLplusplus Release version: 4.20c
AFLplusplus GitHub version: 4.21a
AFLplusplus Repository: https://github.com/AFLplusplus/AFLplusplus
AFL++ is a superior fork to Google's AFL - more speed, more and better mutations, more and better instrumentation etc