The meaning of proffer
Solution 1:
A proffer is an initial (first) offer, or one made at the start of negotiation. There are additional, legal senses of the word (see http://en.wikipedia.org/wiki/Proffer), but that is the distinction I would make for ordinary usage.
Also "implies voluntary action motivated especially by courtesy or generosity", as in (thanks to @horatio)
proffer an apology