You make it as there is huge difference between the two formations, it's not like they stick on place and don't move.

You also don't need both 'wide' players to play the same.
In a 4-3-3, I typically want one of them to be very inward-looking - focused on getting close to the main striker and getting into goalscoring positions - and one to play as a more orthodox winger - staying wide, stretching the game, looking to get crosses in.
