D7 - does drush rr ALSO clear cache? Someone just told me that in D7, drush rr and drush cc all do the same thing. I can’t find anything that explicitly states the difference, nor can I find anything that supports such a claim. Additionally, I’ve noticed there are some changes that seem to only show up with a drush cc all, particularly changes to code. Do drush rr and drush cc all actually implement the same functionality?
See https://drushcommands.com/drush-7x/registry-rebuild/registry-rebuild 

drush rr has the option:
--no-cache-clear : Rebuild the registry only, do not clear caches. 

drush rr rebuild the registry + clear the caches.
drush cc clear the caches only.