This one is similar to the one on the difference in guys between the three genres of anime.

Shoujo girls--normal sized busts, bigger and more detailed eyes, more detailed hair

Midway--Busts will differ since it can be for both genders. Sometimes fan service, but only rarely. Kill la Kill is not a good example.

Shonen--big busty women with big hair and crazy details. Fanservice is a must. Kill la Kill is a very good example.