Anybody out there know the diffrerence between the APC 20x10W and 20x10 standard propellers. I will be using the prop on a Moki 2.1 installed in a 1/4 scale Extra 300S and want the best prop for vertical and aerobatics?

Blade shape mostly. The W series props have larger average blade chord. The different shape does place a little more load on the engine. (gives a bit better vertical performance in most cases)

I'm from the school of "Experiment with LOTS of props." I'd buy one of each, and compare performance on the aircraft. You are likely to find your preference will differ from other people using the same engine and aircraft...

Forget the apc entirely and go with a zinger pro wood. Apc props that size are very heavy, dont spin up nearly as fast as wood and really arent any less prone to break due to almost any strike on an apc damages the sharp tip. A mejlik carbon fiber would be even better if you can find one.

The 20x10 W has the blades that looks like Zinger Pro blade
while the 20x10 has a blade that looks like a thin double-tapered wing, with a very small tip chord width, like 10% of the root chord width.

I believe APC makes this tapered shape prop in their larger prop is mainly to reduce the weight (inertia) to improve the spool up. The wide props that are larger than 18" are very heavy, and the corresponding glow engines just don't have enough torque to spool up these large wide heavy composite props quickly. The 20x10W is a more suitable prop for a 3.0 gasoline engine, which has more torque than horsepower. Your Moki 2.1 would do better with the 20x10, with much faster spool up and about 400 more rpm.

I read a review on the Moki 2.10, and they said maximum thrust is obtained with a Moki 20x10 prop of 25 lb, claimed by the manufacturer. I think they are the same as Bolly. When prop size is over 18", APC is no longer the king. Especially for a 2-stroke glow engine, lighter props spools up better for that size.

Thanks for the advice gentleman.