Japan's Metal Gear Solid Integral not only contains more VR Missions but it also contains a first person view feature in the game. This feature allows to walk and look around(but can't shoot your weapon) through Solid Snake's eyes in regular game mode. North America's Metal Gear Solid VR Missions has this feature but it's hidden within the game's coding. The only way to enable this feature on MGS VR Missions is using a cheating device (Gameshark).
In original Japanese PlayStation version of the game, the jail guard (Johnny Sazaki) is left with his underwear on when he is stripped by Meryl when she escapes. In the North American and European version of the original, he is completely naked with blur on his butt. This was changed back in Metal Gear Solid: Integral (1999), as well in the PC version.
The original Japanese Metal Gear Solid was released with one difficulty level. When brought to America, it was released with three additional difficulties, as well as some additional hidden "Easter Eggs", including a hidden tuxedo costume for Solid Snake. Later on, the American version was re-released in Japan under the title of _Metal Gear Solid Integral (1998) (VG)_ , moving the VR Training missions from the original two discs to a third disc, providing over 300 missions total, as well as three movies containing promotional footage shown during the 1997 E3 Show and '98 Tokyo Game Show. This special edition, contains a fifth difficulty level, as well as another new costumes, Meryl in Snake's sneaking suit (inspired by the Metal Gear Solid Drama CD series released in Japan), and all the new additions from the American Metal Gear Solid.