Originally Posted by
Excalibur
My learned friends above have given the technical answers, which are entirely correct, but may not help you in your choice.
Band pass cabs produce a different type of sound to bass reflex cabs. I'm not fond of it. I'd recommend hearing thje two side by side.
My numpty guide is that if you can see a speaker behind the grille, it's bass reflex, if you can only see slots, and no speaker cone, it's a band pass. That's only scratching the surface, but might help. In my humble opinion, bass reflex are more musical.