The green will run cooler and quieter...and slower. The Barracuda will run faster and hotter and louder (but not all that hot or loud). Basically, they're not comparable drives. You might consider a WD Blue instead - it's pretty much in the middle.
I've got two 3TB Barracudas in my daily driver and they average 32C-33C. If they're working hard and I have the side panel off, I can hear them, otherwise I can't.