In the 1931 (?) American film,  "The Music Box",  Stan Laurel & Oliver
Hardy move what Americans call a "music box" to a new home.  It is quite
large, plays from a paper roll,  and has a mind of its own.  "Musical
Boxes" ( or "musical box" if you are referring to just one of them) are
small wooden boxes, that make mysterious sounds when the drawers are
pulled out or pushed in --  usually found in San Francisco's Chinatown
for sale to tourists.

I have heard "music boxes" that were not very musical, like the ones
which play Taiwanese arrangements of "Send In the Clowns".

I hope this clears things up once and for all.  ;-)

Bon jour,

S. K. Goodman