Compare
Blues vs Pentatonic Minor
Blues adds one note — the ♭5 'blue note' — to minor pentatonic. The six-note set unlocks slide-guitar and bent-string vocabulary.
Blues
R
♭2
2
♭3
3
4
♭5
5
♭6
6
♭7
7
Pentatonic Minor
R
♭2
2
♭3
3
4
♭5
5
♭6
6
♭7
7
What's different
Only in Blues
♭5
In both
R♭345♭7
Other comparisons