There are so many different types because they are all used for different purposes in different situations.
http://wiki.answers.com/Q/How_many_types_of_reception_do_you_know"
Emo screamo, Hardcore screamo, Metal, Pop rock, Rock, Hardcore rock, Hardcore metal, Soft rock, Punk, Hardcore punk, Pop punk, Jazz, Emo, and Rap!! :) Ps. My favorite is Hardcore screamo and Metal!...
Really, none are! That doesn't mean they're edible though.
there are three known speies