Complex sentence: All-female bands in which members also play instruments are usually considered a separate phenomena, and these groups are sometimes called "girl bands" to differentiate, although this terminology is not universally followed and these bands are sometimes also called girl groups.
Split into simpler sentences: All-female bands, in which members also play instruments, are usually considered a separate phenomena. These groups are sometimes called "girl bands" to differentiate, although this terminology is not universally followed, and these bands are sometimes also called girl groups.