Quote (mysticsword353 @ Jun 17 2013 02:48am)
The difference is 40% life leech

And the ability to leech off monsters that don't let you leech normally.
(...)
No, because life tap ignores :
a) Difficulty penalty on leech (Hell = 1/3 IIRC)

monster's resistance to leech (which was a part of your answer, but concerns every monsters, not only those unleechable).