The only difference is one is green and the other is red. Their purpose was to show the difference between the green/red versions of the games so some do have different pokedex info based on the game. Like ekans not available in green, or sandshrew not available in red, etc.
The cards came out with speculation about the video game. In reality the game ended up being Red and Blue. Some of the green and red cards say they are traded (“exchanged”) from the other color.