While Metal Gear was a big success in Japan, Konami wanted to release it in the West, too. MSX were only released in Japan, so they decided to release it for another console instead. And the only console that was really big in the US and Europe back then was Nintendo Entertainment System (NES). Nintendo didn't allow their 3rd part manufacturers to release more than five games for the console each year, but Konami got past that rule by creating the company Ultra Games that released Metal Gear in the US instead. That's why there is no Konami logotype on the title screen of the US version. In Europe the "real" Konami released the game. Metal Gear was released in the US in 1988 and in Europe in 1989.
The NES conversion of Metal Gear is not identical with the MSX2 original. NES's capacity is a bit weaker than MSX2's, so the graphics are not as good. But Konami did also change some of things in the game's plot. In the MSX version, Snake begins his mission in the sewers of the base, while he in the NES version parachutes into the surrounding jungle. Some of the characters Snake meets in the original version were also nowhere to be found. However, Metal Gear for the NES was still a big success, and made gamers all over the world to get their eyes on a game series that today is classed as one of the most classical ever.