In Japan, Contra 3 is known as Contra Spirits. The general gameplay is pretty much the same, with some minor changes - first off, there were level select and sound select cheat codes taken out of other versions. Also, you can beat the game on Normal and get a good ending - the American and European versions require that you finish on hard mode.

On a side note, here's a literal translation of the game's Japanese intro:

Yatsu ra...yurusan>/i> - I won't forgive those bastards.

Hade ni demukaeteyaru ze! - Let's greet them with style!

Contra 3 is known as Super Probotector: Alien Revels in Europe. Once again, in the conversion to Probotector, the two player characters have been changed to robots and all of the artwork altered accordingly. Most of the enemies were already robots to begin with, however. Oddly enough, you still have the same human death scream when they die.