from what I understand the fiddle bowing styles of old timey and bluegrass are quite different.
generally[there are probably examples, that are exceptions]old timey fiddle bowing uses a particular slurring pattern,whereas Bluegrass fiddle bowing,the fiddle slurring,has much more variety.,and and more vareied and different combinations of seperates and slurs.
old timey fiddlers would tend to bow eight quavers,slur 2, 2 seperate. slur 2 2 seperate,bluegrass fidlers appear to bow differently.
I apologise if I have oversimplified or generalised,as Iam sure someone can quote a minority of old timey fiddlers who dont bow like this.