Rajon Rondo was All NBA Defensive first team 2009-2010 and All NBA Defensive 2nd team 2008-2009.  These kinds of facts can be found by keying in nba all defense in your search engine. It is part of a section of nba.com called nba awards.
   The shorter Nate Robinson will harrass opposing guards on defense, but can be shot over and posted up.  Also, I have to agree with above posters, even though I have only seen a limited amount of Robinson playing.  Rondo probably is the better point guard.  Also, on offense and defense, Rajon's toughness, intelligent use of his A+ quickness and body control make him play bigger than his 6'-1" highth.  To Nate's credit, its possible he is the better shooter.
   When you compare both players total overall "games", Rajon Rondo is a grade A player, Nate Robinson is a grade B player.