Front Stuffing Pockets have an opening at the front of the diaper for stuffing purposes.
Pros
Poop can't sneak into the pocket opening
No chance of touching the poop when unstuffing the diaper.
Cons
Have to touch the pee soaked insert when unstuffing
Brands with front stuffing pockets: BabyKicks, Oh Katy
Rear Stuffing Pockets have a pocket opening at the back of the diaper. Some are higher up the back of the diaper, while others are an inch or two down.
Pros
You don't have to touch pee when unstuffing the diaper (as long as the insert isn't completely soaked)
Cons
Poop could get into the pocket opening
The poop may be at the opening and you may touch it.
Brands with rear stuffing pockets: BumGenius, Fuzzibunz, Rumparooz
For more information see:
Back to Basics: Pocket Diapers