Yeah, that's the only difference- Assembly.

There is nothing magical about strong wheels. Spokes are spokes. There is no super material being used in high-end spokes. Sure there are differences in design (ie, straight pull vs j-bend) but all spokes rely on tension.

I read somewhere that at "optimzed" spoke tension a spoke can actually back out 9 turns before any tension is lost. Obviously, how they are set-up matters.