Alt Lite are mostly just Trump cheerleading civnats, libertarians and Zionists who have been accepted into the GOP fold, more or less. They have the big follower counts and blue checkmarks on Twitter.

The "alt-right" is basically a collective name for ethnonationalists/white nationalists of various stripes. TradCaths to alt-progressives, manospherians and racially aware white TERFs (yes, that is kind of a thing, a TERF wrote for Radix).

Tbh, I think these terms are redundant now because it's difficult to distinguish most of the Alt-Lite from normie conservatives. Paul Joseph Watson would not look out of place in the UK Tory Party. He is nowhere near as edgy or controversial as he might imagine himself to be, he even distances himself from conspiratards. Although you do get people like Katie Hopkins who sometimes walk a fine line.

The "Alt-Right" is a clusterfuck of infighting and people who hate each other, e.g. Greg Johnson and Richard Spencer.