1Way is absolutely correct. The minor pentatonic and the blues scale are not the same thing. The blues scale contains the b5 which is what gives it its whole character. The minor pentatonic does not use the b5. For example - Am pentatonic is A, C, D, E and G, whilst A blues scale is A, C, D, Eb, E and G. As you rightly say, 1Way, pentatonic has 5 notes and blues has 6. To hear the 'true' blues scale go listen to some SRV. Also the solo to Stairway To Heaven is almost entirely pentatonic minor apart from the occasional use of the note F (b6) which is used to fit the accompanying F chord rather than as part of an Aolian mode.