Watch the Major Pentatonic Scale online guitar lesson by Jeff McErlain from Blues Guitar Survival Guide - Lead
The major pentatonic scale like the minor pentatonic scale is just a major scale with the half steps removed. As its name suggests it produces a more major and happy sound. Generally speaking it is more closely associated with Chicago blues like players like BB King, as opposed to Albert King who has more of a minor Texas blues sound. Of course these are large generalizations but think of them as simple player related guidelines. If it's darker sounding it's minor blues, if it's brighter sounding it's major blues. I highly suggest playing over a major groove to get used to the sound and feel of the major pentatonic scale because if you are not used to it, like anything, it takes time.