I suspect the words have exactly the same meaning in both languages. Even classical music is referred to as popular when the most popular pieces are played (think Class fm radio and light classical music), but the English 'pop' is only an abbreviation that has come to be used for the 'Radio 1' genre. There is probably a similar abbreviation (the same?) for the equivalent music in Polish.
Słuchaćrequires Genitive - that is how Polish works. The question for słuchać is kogo? czego?(GEN) - słucham nauczyciela, słucham muzyki, NOT kogo?co?(ACC) słucham nauczyciela, BUT słucham muzyka. In this case słucham muzyka means I listen to the/a musician (muzyk), not music(muzyka).
Bottom line : słuchać + GEN.