Love these, and the Overhangs, and wanted to compare them for people who have questions about the differences.
The first place you notice is in the weight. In size M, Overhangs are 13.1oz, Thrives are 5.5 oz. You also save some additional weight because the Thrives have small cinch straps built into the sides, so you don't need a belt. Overhangs require a belt, adding a little more weight to the 13.1 baseweight.
Much thinner fabric on the Thrives... Thrives are narrower cut in the legs, go down a little longer, and have only the two front pockets, which is their biggest downfall. Having just one more pocket somewhere -- either in back or as a cargo pocket -- would make these the perfect shorts. As it is, especially with the clingy cut, it looks weird trying to shove cell phone, wallet, keys into just two pockets when you're out on the town.
Overhangs are better for casual/daily wear or for activities -- like climbing or scrambling -- where you're going to be really rough on your shorts. Thrives are better for hiking, active sports and hot weather conditions.
Both have a place in your closet. I've got two pairs of each and have gotten rid of most of my other shorts.