There are laws regulating the max amount of fat in the ground beef. For the US< I found this:
Lean ground beef: Must meet the requirements of ground beef but may not contain more than 22 percent fat.
Extra-lean ground beef: Must meet the requirements of ground beef but may not contain more than 15 percent fat.
Here is the linkie:
http://www.beefinfo.org/Default.aspx...eID=56&SecID=8
ETA
Even says in the same link that if you rinse crumbled "regular" ground beef to remove some of the fat, once cooked, that it has less fat content than lean crumbled beef, undrained.