FTF or Face To Face usually means a dealer isnt involved because the seller intends it to be his face and the buyers face. Meaning you meet up in person and the two nonlicensees complete the transaction.
ATF doesn't refer to nonlicensee to nonlicensee transactions as "face to face", but as "private party transactions". A few years ago ATF revised the Form 4473 to allow for buyer and seller to meet at an FFL, have the buyer complete a 4473/NICS and if successful, only then would the dealer record the firearm in his books. If they buyer did not pass the BG check, the seller never lost possession and the dealer would not record the firearm in his records.
It's become somewhat fashionable for dealers to write on their emailed FFL's "No face to face transaction" because they don't want someone else using their FFL copy to acquire firearms. It's a good business practice when selling face to face to another FFL to record his drivers license info when he hands you an FFL copy in person.