I agree, but Shimano's website does make it look that way. Bring up their site, go Products->Mountain Bike. Alivio is at the bottom of the list, and Deore sits right on top. You have to go over to the Tech Docs menus to discover that there are also Acera, Altus, Tourney, etc.

For some reason, at least in their product info pages, Shimano pretends there is nothing less than Alivio.