The difference may depend on whether you use a straight or helical clamp, and where the feather is in relation to the nock, and if it is making full contact. RW should be used in RW jig, for best results, so the cup in the feather is the surface that catches the air. This is important for rotation in flight.
An air craft wing is designed to lift, same principle with a feather, the air travels over both surfaces. It is more aerodynamic. Plastic vanes which are straight can be used with either jig, but the nock receiver is often different.
If you use a Bitzenburger, they have different nock receivers for straight and helical, but the standard one will work. I prefer the RW receiver with the RW Jig and LW with LW Jig for offsetting the feather at the rear, in relation to the nock index. The feather starts to the left of the index and goes the same distance to the right. Look natural, flies and wears better.