Both are the same type of envelope commonly referred to as a donation envelope, offering envelope or a tithe envelope. They are used for fundraising, money collection, charity donations. These fundraising envelopes contain an inner pocket to hold cash or a check. Donation Envelopes are sealed by a moistenable glue on the flap. The only difference between them is the size. #6 3/4 Remittance: 3 5/8" x 6 1/2" when closed , 7 1/4" x 6 1/2" when flat #9 Remittance: 3 7/8" x 8 7/8" when closed, 7 3/4" x 8 7/8" when flat