Hamlin and Valencia are our two main juice orange varieties. Hamlin is early-maturing (November - January) and Valencia is later (March - June). An ideally matured Valencia will have a richer flavor than the Hamlin, as well as brighter color; but otherwise they are similar. Outdoors in Florida, Hamlin is far more productive. Both are "seedless" in the legal sense, meaning fewer than 6 per fruit. Both will generally make a seed or two. Dwarfing is based on the type of rootstock onto which they are grafted, so if you can get either on 'Flying Dragon' roots, they will be dwarfed.

I have grown all the common orange trees in here in SW Florida. IMHO the only reason Hamlin exists is because it comes in earlier than Valencia. Valencia is the #1 juice orange for a reason. Citrus doesn't grow like Kudzu you can keep a tree any size you want. If Valencia is a 10 as a juice orange Hamlin would be a 7-8. It is lower acid, but not as refreshing and has a bit of a thicker/butteryness to the juice and flesh. It's not a bad orange, just not as good as Valencia or a good Navel.