What is the difference between "Expunge" and "Contaminate"?

Regarding the change that Twitch underwent, I'm curious about what actually changed when this occurred. Apart from the name and the damage, was the only change in "feel" the distance indicator? My friend says when they changed the ability that they nerfed it because now it "travels" and therefore has a missle speed. I can't find ANY evidence to support this, my response is all they added was a visual to what the old Expunge was doing. Can somebody clear this up with certainty? I'm not necessarily asking for a Rioter, but somebody who can provide evidence.