3. Vader had either superior numbers with him or was dealing with one on ones. Revan faced overwhelming odds without much in the way of backup.
4. You make it sound like he soloed everyone in the temple, he didn't, he was being supported by a clone army.
And had the Rep Army and Revanchists behind him. Vader killed Jedi during the time of The Golden Age. The prequel Jedi Order was the Jedi Order in its prime, and Vader slaughtered them.