*Breathes in deeply* FS is for the gameboy and was sold with AlttP. FS requires 2 to 4 people to play. It has only 4 levels which the last has three different difficulties which you may enter depending of the ranking key you have from the three other levels. FSA is for the game cube and you can play with 1 to 4 players. It has quite a few levels with sub levels for each one. FSA actually has a story throughout the game. FS just has a story intro go through the levels and the the story ending. In FS you have to meet the Great Faries to get key to Vatti's palace. In FSA you have to free the madians and go to Vatti's palace to free Zelda, only to fight Ganon.
FSA has a multiplayer feature called shadow battle to fight other players. FS does not have such features. FSA has people, FS does not. FSA has Shadow Link, FS does not. FSA has a much wider varity of items. The two games have different enemies in them.
I don't get them very well either, i just know the adventures was for the gamecube, had a more complete story and i think had better multiplayer than the other four swords that was kinda like a beta for adventures
They're two completely different games. There are HUGE differences in terms of plot, locations, and much more. This is a bit random, but I'm always annoyed when people say 'Adventure' instead of 'Adventures' for FSA. Don't take it personally, alot of people do it.