Probably a dumb question, but...

... what is the difference between vampiric regeneration and 'regular' regeneration?

We'll use "+1" on a weapon as an example.

Regeration +1: automatically heal 1 hitpoint per round while weapon is held (works constantly)

Vampiric Regeneration +1: heal 1 hitpoint each time you hit an enemy with that weapon (basically you take some of their health to heal yourself, only works in combat)

Ah, cool. I thought that might be the answer!