Much like the way major and minor pentatonic scales relate to each other, the blues scale is the same with an extra note added in.
It's a six note scale instead of a five. Let's take a G major pentatonic scale. Its relative minor pentatonic scale is E. It's the same notes a G major pentatonic, but we're starting on E and it becomes E minor pentatonic. Now to play and E blues scale, which is actually the E minor blues scale, we're going to add a note in between the A and the B. We're going to have E, G, A, B-flat, B, D, and then E. Sounds like this. That's the E minor blues scale.
Of course, just like with the pentatonic scales, the major blues scale sounds like this, its relative major blues scale. Just as another quick example let's do the same thing for G minor blues scale. There we've got G, B-flat, C, C-sharp or D-flat, D, F, and G again.
That's G minor blues scale and its relative major blues scale would be B-flat. The same notes except starting on B-flat. That's the blue scales in its basic essence. There's a lot of music to be made with it.