Asiatics bloom early, April-May, Trumpets bloom in June-July, Orientals bloom July and August. Most Trumpets and Orientals are taller than Asiatics and have a different distribution of leaves. There are a few more differences, but those are the biggies.

Lainey

What I have noticed in my garden is that Asiatics spread really well, but don't have fragrance, and that Orientals are beautifully fragrant, but don't seem to multiply very fast, if at all.