The two stable Lagrangian points in a two body system (L4 and L5) are known as Trojan points.

Trojan points are named after the Trojan asteroids, a group of asteroids named, in turn, after Trojan heroes from the Greek/Trojan War. The Trojan asteroids reside at the Jupiter/Sol L4 point; there is also a group of asteroids at the corresponding L5 point, called the Greek asteroids. Of Sol's planets, only Jupiter has been found to have asteroids orbiting around/in it's Trojan points, although some moons have small Trojan point companions (these are planet/moon Lagrangian points, not Sol/moon).

To put it simply*, Trojan points are 'empty' points of space that have their own 'gravity' due to the gravitational forces of two larger celestial bodies. An object in any of the other three Lagrangian points will stay put as long as no other force (besides the gravity of the two bodies) act on them, but will drift away at the slightest nudge. Objects in the Trojan points will drift back to the point if pushed away.

Occationally Greek Points (L5 points) are differentiated from Trojan points (L4 points), but usually they are both known as Trojan points.

* The mathematics explaining what exactly is going on are so complex that I can't understand them; if you think that you might be able to, you might want to check out this site:
http://www.paias.com/paias/home/Science/Newton/Newt3Trojan.htm#Trojan%20Points