ofcourse you can tell, just check the payment details see if theres a fee if none then it was sent as goods / service
by default a gift or personal payment is "ticked" to sender as the one who would pay the fees only even if he does untick it, it would just make his payment look like sent as goods as not it charged the fee on the reciever.
still a gift payment is as good as nothing if you dont know how to securely verify the buyer.