Nothing to say about the SST but if it's at all possible don't use the other for hunting, too much wasted meat, however they are amongst the most accurate factory bullet ever made !
Not much they are both rather explosive. Depending on caliber there can be differences that can be significant. If you look at the 120 NBT in 7mm its not particularly destructive but the 140 NBT in 7mm can be. The 140 SST in .277 is another example of a bullet that is somewhat less destructive than the 140 NBT.
Check out the attached site for your caliber of choice. Neither the SST or NBT require a great deal of resistance for reliable expansion velocity is the single greatest determining factor in destructive capability. If you like to hit shoulders they're probably not the best choice but put either in the boiler room behind the shoulder and results can be dramatic.