like yourself, i am skeptical about how much difference there could be. if i were to take a guess, however, i would say home theatre speakers would tend to focus more on the reproduction of human voices and/or special effects such as explosions and roars, whereas a speaker designed for music would focus more on reproduction of instruments and balancing everything more evenly than one would generally find in a movie.
like i said before, i think it sounds like a bunch of bs.
CMT-340SE2 Mains & Center, CBM-170SE Surrounds, Rythmik F15, Emotiva XMC-1, Emotiva XPA-5