[Harp-L] Blues scale vs. Pentatonic scale

["Guy Buxman" <gbuxman@xxxxxxxxx>]

Playing harp in a garage band and performing at many jams around Southern
California, I routinely encounter guitar players who assert that the blues
scale is merely the pentatonic scale with a few flattened notes.  Now I'm
only just learning about music theory so I don't claim to be an expert;
however the reading I've done recently describes a distinct scale for blues.

If I understand it rightly, the blues scale is:
I + III b + IV + V b + V + VII b

and the pentatonic scale which, according to David Harp, is most commonly
used for country/western is:
I + II + III + V + VI

Is there any real correlation between the pentatonic and the blues scales?

- GB