It's not a real mystery. Sub manufacturers know what kind of audience they are building particular gear for, and so optimize the performance (frequency response curve) accordingly. A "musical" sub is one that is geared toward people who use them primarily for sound
reinforcement of the lower frequencies rather than as a sound
effects in a musical circus.
YouTube is awash in videos graphically illustrating the difference between the two. And we are all unwillingly exposed to the latter every time we stop at a stop light or gas station with "auto-files" determined to impose their lack of taste on every other motorist unfortunate enough to share the highway with them.
GeeDeeEmm