The difference between the two is, Nuzzle gives you 1 Karma point. Bite takes away -1 Karma; example. If I had 0 Karma and someone 'bit' me I would have negative 1; aka -1. So then Nuzzle, I have 0 Karma someone 'Nuzzled' me I would then have 1 Karma point.
Hope this helps you,
Old_Yeller
![Wink ;)](https://feral-heart.com/smf/Smileys/default/wink.gif)