Leonard is a good overall athlete, but he isn't that explosive vertically. He tested with a 25.5" no step vertical, and a 32" max vertical. His crazy length makes his leaping ability seem better than it is because his arms get so far above the rim. Looney is the same way (they both have 7'3 wingspans).
They both have good lateral agility and can guard both forward positions to a degree.
Both good rebounders.
Both are more unselfish, reserved players.
You could say Looney is more of a PF, and that's probably true to an extent (partially because he's nearly 6'10), but I bet Leonard posted up more at SDSU than Looney did for UCLA (only 9.3% of Looney's offense came off of post up situations). And Looney's jumper is way better than Leonard's was in college (Looney averaged 42% from 3; Leonard only 25% in his two years of college).
If Looney's game translates, I think it'll be in a similar fashion to how Leonard impacts the game. Hard nosed, smart defense; spot up 3s; driving when the defense overplays him; making the right pass; posting up occasionally; etc. Whether he can come up big in pressure situations like Lenoard is the real question and the thing that is most often failed to be mentioned when comparing any player to Kawhi.