How do you see them differing? I think a zap can be universal--used for all kinds of things (including indicating approval). Likes are essentially superfluous...
Zaps are money. Inserting the exchange of monetary value into social interactions online where they didn’t exist before, the way zaps are doing, is an interesting and exciting thing to witness and be part of. I think it opens a lot of possibilities but I also think it introduces some issues and dynamics we didn’t have to think about before. Money just changes people. How zaps are implemented is an important thing to consider and study and adapt with as time goes on.