In practice - sonically, very little, the crossover point of the 745 is a little lower than the 735. Consequently, the 745 should be able to handle more in the woofer department as the horn in the 745 can take on a little more than the one in the 735. The woofer voice coil itself is larger in the 745 so you are going to get a little extra in that department too. For use with bass and guitar, I doubt you would tell the difference. Maybe if you tried the 735 and 745 side by side with vocals you'd notice something... but I've never done that specific test. 735 or 745, they are both class acts and certainly better speced and performance that most of their counterparts with the same retail price.