Pentatonic refers to any scale with five notes. One can split the intervals in a variety of different ways. The primary ones we use in Western music are major pentatonic and minor pentatonic. See here:

http://www.guitartricks.com/tutorial.php?input=296

Some Oriental systems (and therefore Eastern music) use different arrangements of intervals. See here:

http://www.guitartricks.com/tutorial.php?input=40