The regular has silver foil stamping on them while the factory sets had a rainbow/holographic foil stamping.
The Factory RCs are RIDICULOUSLY hard to find, yet the sell for so little. Topps goofed on the redemptions and instead of sending out factory style (holofoil) RCs to people who redeemed the RC redemption card, they sent out silver (regular) RCs. I would guess there is one factory RC for every 1,000 or so regulars (feel free to replace that 1,000 number with something higher as this stuff was pretty mass produced).