I myself would be far more interested in the Japanese Blue than Green. Green has the same encounter tables as the American Blue version, but the Japanese Blue has encounter tables that have never been seen outside of Japan, such as wild Jynx in Seafoam Islands(Since Red had Electabuzz and Green had Magmar). The international Red and Blue versions use the Red and Green encounter tables/in-game trades while using Blue's Graphics and Cerulean Cave layout.
Also the Japanese versions of the 1st gen games did not have colored cartridges or anything like that. The Japanese 1st gen games used the standard grey cartridges(And as another note Gold and Silver used the black cartridges Color games had). Crystal was the first Pokemon game in Japan to use a colored cartridge.