Yes there is, for classroom training there isn’t really any hard rules, basically anybody is allowed to do that, don’t even have to be a pilot. The ATO has to make sure the classroom instructor is performing to the ATOs standard.
Then for practical training there is a Flight Instructor (FI) license, for bigger planes Type Rating Instructor license (TRI) then there are all sorts of additional endorsements like instrument rating, night qualification, multi-engine. A beginning FI is “restricted” so he can’t sign off first solo’s until he gained some experience.
Anybody can of course say he is an instructor and post some nonsense on Youtube.