The tune of a song (曲) is created when the song is sung for the first time. The music accompaniment (篇曲) comes after, when music is created to follow the song. There can be more than one music accompaniments to the same tune, with different choice of musical instruments and different types of vocal accompaniments. More importantly, many music accompaniments do not follow the tune of the song at all as it 'accompany' the song. Or the song can be sung plain, without any music. Is music accompaniment accredited with copyrights? In most countries, no; especially when the music follows the tune of the song closely. The song, lyrics and tune have copyrights. Sometimes, it is possible to split into separate copyrights for the the lyrics of the song and the tune of the song.
A song can be sung to a different tune. As such, some countries award copyrights to the lyrics of the song only. Only the words count.
But both the lyrics and the tune, are the same act of creation as the song is written. A different tune later based on the same word, is another act of creation, tune only. A different set of words based on the tune of some other song, is also an act of creation, lyrics only.
If a piece of music can claim originality; so can anyone else. Many pieces of music can be created based on a tune, or on fragments of the tune to a song. It is easy.
There have been cases when a piece of music having given originality, make further claims of originality on the tune from the song on which the music is derived. That is wrong; made possible because people mistake music accompaniment and the tune of a song to be the same thing. Setting new lyrics to a song written in another language and released as an original creation is just thievery. A Japanese song start different from a Mandarin song, because these languages sound different and so, the first note has to be different. It is just awkward, otherwise. In this case, 'otherwise' mean from overseas.
Have a nice day.
