It could also be a V3! Anyway, you can tell them apart quite easily if you follow this list:
^_^ V1's have a little string of metal spheres attached, V2s and V3s have a short, curled plastic ribbon thing
^_^ Boot it up! If the baby is a cirle/semicircle (black or white) with no legs, it's a V1. If the baby has little legs but is all the same colour (either black or white), it's a V2, and if the baby has one bottom colour and one top colour, with little "antenna" things, it's a V3.
V1s and V2s have no "aerial", V3s have a little aerial at the top left.
There you go. The middle one is the most helpful, though.
V2 and V1 have different games. Go into the Game menu. Version 2 has four games: Jump, Bump, Heading, and Slot. Version 1 has two games: Dance and Jump.