Yes I understand...but why not JUST the blues scale as it has ALL the notes?

ie All the notes in the pentatonic PLUS the added note.

I'm guessing the answer is sometimes one might play exclusively within the pentatonic which will give a certain feel...and then playing with the blues scale adds a different 'feel'?

To be honest a lot of my attempts at improv sound the same :(

Anyway, I'll try to keep practicing both.

Thanks