The Tippmann Factory F/A is based on the Pro-lite, and uses the same valve, grip frame, and barrel, but they have a few very important design differences.
The first is obviously the cyclone looking feed on the side. It's not a Cyclone though, it's known as the Star feeder. It's not air powered, you actually wind up a spring to power it. Not particularly reliable, and you have to wind it up every 50 shots or so.
The second big difference is the extra bits on the top of the body, in the rear sight. Those are two small hydraulic pistons that make a kind of shock absorber. Now I bet you're wondering, why doe this thing needs shock absorbers on top of it? Well that's because of the third difference...
Yep, the F/A stands for Full Auto. Rotate the safety all the way back and when you pull the trigger the sear stays down and allows the gun to free cycle. The shock absorber is attached to two additional sears which briefly grab the hammer at the rear of the travel for a brief moment, preventing the gun from being a paint blender. Since this gun was released back in 1995 there's wasn't any force feed hoppers on the market, hence the wind up force feed hopper bolted to the side.