In Bf:1942 yes you can be a foot soldier... its like a fps your a soldier running around but you can get into vechiles.
And yes in Mods you can use vechiles also.. like they have their own vechiles.
like in EOD and DC they have Helicopters
and Jets, Humvees,
its really a fun game.
WHat i think is.. Call Of Duty is fun for singleplayer and once you bet it that pretty much it.. Multiplayer is ok but not good.
BF:1942 Singleplayer is nothing great.. But Mulitplayer is hours of fun.. if you get board with the game
download a mod play that for a few weeks then when board download a new mod...plus you have have as many mods as you want installed at 1 time so you can switch back and forth.
To see what the game is like go to
www.bf42.com
and goto the forums mabey just see what people are saying look at some screenshots read up about the mods..
you will learn the most there.
Hope all that helped you.
In Conlusion: BF:1942 is a better buy.. as it will keep you attention much longer.