Original Tuff II's made until 1985 used the alloy or metal flanges. In 1986 the wheel mold was changed to incorporate the hub directly into the wheel. That revision stayed in place until 2005 when the loose ball bearings were revised to a sealed bearing system that is used today. The wheels that are sent to distributors and bikes shops overseas are "OEM Tuff wheels" and use extra long axles ( to accommodate use of pegs) and with reflector holes. Wheels that are sold through me (Planet BMX) use standard axles, and do not have reflector holes.
The big difference is that Avocet Sports ( Coyote) over there in the UK buys the wheels from Skyway for use on their bicycles, so they are considered "OEM" to fit the needs of the bike manufacturer and some are used for their complete bikes, while some are sold individually to bike shops.
I sell the "aftermarket" version, that does not include reflector mounts.
That is the difference in the wheels that are out there. I hope this info helps!