The Japanese version, Space Bazooka, was released a year later after its initial release in North America. The Japanese version features slightly different endings than the western version of the game. If the player completes game on the Normal difficulty setting, the background during the closing credits will be decorated with an image of the main character Mike Anderson standing besides the Falcon (in contrast to the blank blue background used in the western version). If the player completes the game on the Hard difficulty setting, Mike will be joined by Tasha, Antonov, and Eddie (the characters who assist Mike and the player during the final battle) as well.
Source: Wikipedia, "Battle Clash", available under the CC-BY-SA License.