Physically no, there's no difference. But there is a difference in clock speeds/memory speeds. The non-OC version is guaranteed to run its rated speeds, but may or may not go much higher with user OC. Possibly fail before getting as high as OC version. The factory OC version is binned (tested at factory) to be guaranteed to run at faster than the non-OC clocks.
You pay extra for the extra guaranteed ability, or pay less and take your chances.
Yes. The cheaper one. At the end of the day, OC on any gpu doesn't really do all that much, OC on a 2080 is still just a faster 2080, it's not going to be in the 2080ti range of ability.