Two different types of mounting systems and bi-pods. I like the versa pods used in conjunction with a spigot on the front of the stock. The all steel versa-pods solve the durability problems that the aluminum ones have (still not horrible). The harris pods are fine, nothing fancy, get the job done.
I will chime in here. I used a Harris clone during sniper school both times, and it worked great, I had no issues, and I beat it hard. We had to use them on uneven terrain, rapid deploys, and were constantly forlding and unfolding them. Mine did fine. I also noticed no problems with guys who were using harris or versapods, no one had a failure except one guy lost a nut off his, but that was fixed in ten minutes, and it was on a harris.
All in all if you use the gear the way it was meant to be used, and buy the pod that fits your needs, you wont be let down. Dont buy a short pod if you need a tall one, keeping the legs extended exposes the weak point of any bipod, as all the stress is on the thin part of the legs.