>>881953Acquiring all 1000 moons is a total grind because a lot of them are secret or otherwise total bullshit (there's one where you have to literally just stand in one point shooting coins at a plant for 5 minutes to get a moon), but there's no reward beyond getting the first 500 - not even an acknowledgement for 100%ing. You aren't actually supposed to do them all, and getting 500 isn't too bad.
I 100%'d SM64 last year in about 4 and a half hours, so in that sense I would say 64 is "easier", but I remember I never managed to get all 120 stars as a kid so I don't know how Odyssey compares for children.