topic. nds can play online and wifi. psp can anot ah
that will depend on the game. almost all games can play with other psps, name for this is ad-hoc. online (infrastructure) games are fewer, but usually those are better games.
psp has a wifi built in. which enables you to surf net with the psp. the wifi is also used as a link between two psp which enables you to play games on the psp with your friend who has another psp.