Cassette film is the correct term for rollfilm delivered in a two-spool package in which it stays when exposed by the camera.
Some call such film packs cartridges, but "cartridge" is a more general term which also comprises 120 film rolls and other rollfilm types which are delivered on just one spool. That other kind of film rolls are called film cartriges because they resemble hunting ammunition cartridges!
We can define: Rollfilm CARTRIDGES are delivered on ONE spool, CASSETTE FILM is packaged in cassettes which obviously contain TWO spools, the first with the unexposed film, the second to coil the exposed film so that rewinding film becomes superfluous. Film stays in the cassette when it's exposed by the camera.