From what I know, Dan...
Green was a promotional version of the games, not available in stores. Due to it being a Promotional version, it was blessed with gaining a Mew when you collect all 150 Pokemon.
However, Nintendo wanted Mew to be a Nintendo-event Pokemon, so they had Green changed into Pokemon blue and released as a normal game alongside Red, instead of being a promotional game.
People merely insist that Green was no different to Blue, and although that in a way is correct, Green and Blue weren't the same game, just as Red and Yellow aren't the same game (Very minor differences, I mean).
Of course, I could be wrong...
As long as we continue to fight, and destroy, we are forever prisoners of our ignorance and foolishness; true 'freedom' does not exist