don't have pictures, but...

A Roll Crimp is a slight inward roll of the cartridge case into the crimp groove (cannelure) of a bullet. It can't be used on bullets without the groove.

A Taper Crimp just "tightens" the casing around the bullet -- essentially, it removes the slight belling that occurred with the expanding die to allow the bullet to smoothly enter the case.

(Ron -- you covered more ground! Semper Fi. --vic)