EDIT: One moment please, @StudentScissorsLeaker.
You mean this comment?
The Av-Matoran were the only type of Matoran that had a build specifically for Matoran of their element, so we classify it as the Av-Matoran build. There is no Ta-Matoran build, or Le-Matoran build, because they never had a body structure that was unique to their element.
In conclusion, Av-Matoran is a type of Matoran build as well as a type of Matoran.