actually they are the same game, outlaw was atari's release and gunslinger sears, basically the question was which cover do you prefer. Gunslinger does have a picture label, it is just fairly hard to find, and like much of the sears art, AWESOME!
Quick story on the game, there was a "fastest completion" on one of the target shoot tracks, and someone figured out you could slip past the barrier in the middle and just start nailing the target, was pretty funny, but totally stunk up the track.