Technically, if there is a minor pentatonic scale (with or without any 'blue note') there must be a relative major pentatonic.
Must be a relative major? Why, or where can I apply that info? What is the major relative of the six note blues scale (I think b5 of E is m3 of G, for example)? Basically, as far as I understand scales is that any scales can be seen as modes, meaning that a five note minor pentatonic has five modes, depending which note you start from... one of which is the major pentatonic. Not all scales are major or minor, but any scale that has 5 notes is a pentatonic.
I too think the original poster must have seen the minor pentatonic scale patterns that cover the whole fretboard. The scale itself is just the 5 notes, the patterns are just a practical tool for "seeing" and playing the five notes. The minor pentatonic in E is the open, 3, 5, 7th and tenth frets of the E string. What commonly is called the blues scale would then add the note at the 6th fret to that.
As far as scales played in blues, of course there can be seen to be many. It depends on the style of blues, some are jazzy or sweet, some sorrowful or blues rock. Minor pentatonic and six note blues scale are the common basis. But major pentatonic (or mixolydian) and dorian modes are very common as well, for example, those just have some more notes in them. So, for example, dorian is like and extension of minor pentonic, like blues scale is.
You don't necessarily need to know the scale or it's name to be actually playing it. You can be playing the minor pentatonic all along, but using some extra notes in passing (bending or sliding, for example) if you so feel. Also, in my view of things, if the backing track chords change, in essence you scale will change as well if you keep playing the same notes. You play the same notes, but they sound different if the chords (harmony) behind it is different. I think you should practice with your head (thinking) and play with your heart (expressing emotion). Meaning when you actually play, I think the point is to forget scales, instead think about scales when you transcirbing or something.
