I am not a musician, nor even a musicologist; I am self described "audience." But I do have a number of records and CDs featuring Bluegrass, ditto old-timey music.

It seems that Bluegrass is a more stylized music, generally using nearly the same combination of instruments, with the vocals sung by a high tenor. Is that because Bill Monroe was himself a tenor?

Old-timey music utilizes a wider variety of instruments, on the whole, including dulcimer, auto-harp, etc. There is less standardization of the music. My wife is wont to call the vocals 'no teeth music', but what does she know?

Here in southern California of a Sunday morning we have a radio program call "Bluegrass, Etc.", www.kcsn.org, 6am-10am local time. It is a program of old-timey and gospel musics, as well as Bluegrass. Once when I phoned in a request, I noted to the host that a little Bluegrass goes a long way, and I hoped he would program more 'Etc.'.

PS-I tried to a blue clicky thing for KCSN, but got an error message, but that is the correct location.