It should also be worth noting the Japanese version of Contra 3 and Hard Corps is suppose to be patched later after game release, which is kind of a big deal as well. Hard Corps is almost a different game since they cranked up the difficulty to an insane degree for the West. The original Japanese version has a lifebar so you can take 3 hits before you die. This was done because the game was designed to be a more action packed, boss fight oriented game so taking hits was more likely to happen, hence why the developers added a lifebar to balance out the gameplay change compared to previous game.
So when Konami decides to remove the lifebar for the West because they don't like people renting, it completely destroys the games difficulty balance and leaves behind something with an insanely unfair, similar to what they did with the 2nd half of Castelvania 3, except now the entire game is like that.
Then for the Japanese version of Contra 3 while not a huge change gameplay wise, is certainly more player friendly. In the Japanese version of Contra 3 you can see the games ending if you beat it on Normal, while the Western version requires being beaten on Hard to see. The Japanese version also allows the Konami code to be input for 30 lives while that was removed from the West as well.