I think with Ewan MacColl there is a clear delineation between songs he wrote or co-wrote, and other songs that he recorded (mainly traditional songs, but MacColl recorded an album of Robbie Burns' songs as well). The one place there is sometimes confusion is whether a song was composed by Peggy Seeger or Ewan MacColl, as they were close collaborators.

In the case of Burns, he adapted folksongs as well as writing original poetry. So sometimes you will find a Burns version and other versions of a song such as Aye Waukin' O or The Curragh of Kildare.

I was thinking of what we would sing to commemorate Pete Seeger (birthday 3 May). He wrote songs but was more important as a performer and leader. There are also songs which Pete had a part in adapting and arranging, such as We Shall Overcome and Wimoweh.