We've just seen how country/folk/irish/bluegrass/etc styles commonly use major pentatonics. Two other styles we might want to explore are rock and blues.
Rock and blues normally do not use major pentatonics -- instead, they use minor pentatonics. However, this doesn't confuse things -- because a minor pentatonic is exactly the same as the major pentatonic one-and-a-half steps higher!
Thus, an E Minor pentatonic contains the same notes as a G Major pentatonic. The only difference is that you might start playing with the "E" tone instead of the "G" tone (or you might not -- depends on how you feel at the moment!)
An A Minor pentatonic has the same notes as a C Major pentatonic, a D Minor pentatonic contains the same notes as an F Major pentatonic, etc.
If you're playing in a blues jam, the jam leader might holler "blues in E". If you're playing real blues (slow and sad -- ex: "The Sky is Crying") the odds are he means E Minor. If you're playing "jump blues" or "shuffle blues" (snappy and bouncy -- ex: "Pride and Joy"), then he probably means E Major.
If it's E Major, then play your E Major pentatonic. If it's E Minor, play your E Minor pentatonic -- which is the same as your G Major pentatonic! You'll use the same notes, but you'll play them in a different style. (In fact, in blues I think the style is more important than the notes! That's why "you got to have soul to play the blues!")
Here's a sample blues "lick" in A Minor (which uses the C Major pentatonic scale). This means that you're playing a seventh against the A Minor backing (the seventh for A Minor is the G from the C Major pentatonic -- basically, a seventh is a step below the root's octave).
This seventh dissonance presents an "uneasy" feeling that works well with the blues. Many blues licks also add a "diminished fifth" -- an extra note that is one half-step below the fifth. In E Minor, the notes would be: E, G, A, Bb, B, D. The "Bb" is the extra note (the diminished fifth).
Finally, let's look at rock and roll. Rock does something completely different. It usually doesn't use minor keys -- but it often doesn't use major keys either!
A rock chord often has ONLY two notes -- the root and the fifth. This is also called a "Power chord". Think of the beginning of "China Road" by the Doobie Brothers. That "CHANG CHANG--chucka-chucka" is particularly driving because it's a power chord!
Since a power chord has no third -- and since it's the third that determines whether you're in a minor or a major key -- this means you can get away with playing a minor pentatonic with the same root as the power chord. Thus, if you're playing in E, you can play an E-Minor pentatonic! If you're playing in A, you can play an A-Minor pentatonic. This makes rock solos particularly easy to do.
Now, you can also play the major pentatonic -- but it probably won't sound right. Major pentatonics tend to have a bouncy, perky feel. This works fine with country, but doesn't always work with rock and roll. Even if the rock and roll song is not using power chords, you still may decide to use a minor pentatonic!
So is it confusing? Maybe so, but step back a second, 'cause it doesn't have to be:
If you're playing country/irish/bluegrass/etc, play major pentatonics in the key of the song ("Jam in G" means G Major pentatonic)
If you're playing shuffle blues, play major pentatonics in the key of the song ("Shuffle in G" means G Major pentatonics)
If you're playing real blues, play minor pentatonics in the key of the song ("Blues in E" means E Minor pentatonic which has the same fingering as a G Major pentatonic)
If you're playing rock, play minor pentatonics in the key of the song -- even if it's not a minor key! ("Rock in A" means A Minor pentatonics)