Binnorie, Cruel Sister, Two Sisters, Twa Sisters, The Wind and the Rain - are these all variations on the "same" song or, are they really two DIFFERENT songs in their historical origins, but they have enough similarities that people, including performers, confuse them?

They both involve a jealous relationship between two sisters, but broadly, there seem to be two distinct flavours -

1. The younger sister goes swimming but the older one won't help pull her out of the water so she drowns and floats downstream to the miller's pond (who sometimes is complicit or related). But pretty much it ends there.

2. The older sister pushes the younger one in, who drowns and floats downstream until her body is found, a harp is made from her breastbone and hair, and when played the harps accuses the older sister.

Is there any historical source research on this/these song(s)?

Thanks in advance.