I am sitting down. and yes there is a difference between a skin and a plane(ingame). for a invisible plane(ingame) you would have to have all the skins for the plane with millions of colors in its format. It is possible to let a skin go by with a milliion colors because if you dont check it in game and it is not on 256 (you cant tell the difference almost) the plane would appear invisible when you select that skin.