Yes it uses lightning. I'm not sure how lightning payments on nostr work, presumably it looks up in the nostr profile the lnaddress and then your wallet makes a payment to that address. Then they call it a zap because, nostr.

But the note you can attach to a zap, that also appears in Nostr clients. Is that a 'note' in the same way a post on nostr is a note? Or is that another note that just somehow appears here?