Well...looking at scales you can say this:

I suppose you know the pentatonic scale...

the difference between the pentatonic scale and the blues scale is just 1 note!

This note is called the 'blue' note and makes certain licks sound bluesy.

check it out: look at the pentatonic scale in the key of A in the 5th position.

and now look at the blues scale (same key, same position)

You probably see the blue note. it's at the A-string at the 6th fret, and (1 octave higher) at the g-string ;o) at the 8th fret.

I believe this is what chris mood was telling you, i just rephrased it i guess...

bubye