Tarmack
Rhetorical Porcupine
Display/ Overlay are cost per impression ($10 per 1000 page visits etc)
Trueview/ Standardview are cost per view ($0.10 per each view were an ad showed etc)
Gonna dispute this. Those may be true of Doubleclick as I don't have any experience with it, but my Adwords campaigns run at a $0.01 CPC/CPV on both Trueview and Overlay.