I think it is appropriate and useful to distinguish
between two words that have been thrown around
up-thread, and in Mudcat generally, namely folk
song and traditional (or trad).

If you are talking about "folk" song, at least
to my understanding it is bound by certain
characteristics:
1. Passed down through some indefinite but long
time by serial oral presentations and memories.
2. No original composer is known to the populace
passing it down, (nor even to scholarly investigation.)
3. And because of the many rememberers and performers
during that long, indefinite time, there are likely
multiple versions of the song, some of which may have
become wildly different. On the negative side, an
absence of significant variants strongly suggests a
non-folk status.
4. A folk song, by this definition, is a special sub-set
of traditional song.

But the unadorned adjective "traditional" merely
means that the song is fairly widely known, and the
singing and remembering population often doesn't know
and probably doesn't care who (if anyone) originally
wrote it. An additional characteristic:
    Lack or paucity of variants probably implies that
much of the spread and (possible) longevity of the song
was because of its preservation through printed versions
and/or recordings.
    Or the song may be much more recent than what is
typically thought of as "folk" song, and thus it hasn't
accumulated many or significant variants during its
relatively short lifespan.

Dave Oesterreich