Can you tell me what's the difference on your credit report of SIF-settled in full vs. BIF-bal paid in full?

We have a credit card account in collections that we've been paying on faithfully for 15 months and the issuer has offered to "settle in full" for 40% of remaining balance (savings of almost $1700) - is this a wise move? Is a "BIF" light years better than an SIF? Will the BIF raise my credit score significantly more than the SIF? please advise : )