There is only one type of Gateway card. That is the red card.
There are different firmware versions: Gateway, Omega, ULTRA. But those are just software.
If you have a 3DS with a firmware < 4.5, you also need to get the blue card as well. The blue card is an NDS flashcard used to activate the profile exploit in <4.5. Some people have stopped selling these with the red card for the reason that they are not really as desired at this point.