I think its all hip hop, just a different style of hip hop. Personally, I think for something to be classified as hip hop it just needs one thing: the music. Thats the unique thing to it; it has a different sound to rock, pop, metal, etc.

Then u can split it up into categories... for example, if the vocals are sung, then its RnB, if they are spoken, its rap.. then u can break rap into poetic, intellectual, gangsta, etc.. its all just different styles of hip hop for different people.. personally, i enjoy all of it, as long as its meaningful and showcases some of the artists skill