Jessup - less grippy, a lot more malleable so it forms to the board better, glue is super sticky so once that shit is down there ain't no peeling it back up and reapplying it if you got it on wrong. The sides have always shredded, chipped away and peeled up on me super easily even after sanding. Remember when they had that huge batch of defective grip where it would just crack away at the edges?
Mob - more grippy, stiffer and less sticky glue which makes it hard to get it to stick to the board a lot of times; because its so stiff though it makes it a lot easier to cut and get a clean cut in my opinion, jessup is a lot flimsier which makes it harder to cut and get a clean straight cut. Will crack super easily if you bend it even a little.
Jessup is cheaper, so I usually just get Jessup. But it's either/or for me, both have their pros and cons.