The difference is clear, the 4th century copies of the real Gospels are widely ackowledge to be copies of text written in the 1st and early 2nd century. But the "scholar" offering this 4th century Gnostic discovery has no basis to claim that it is a copy of text written earlier.
Apparently there are some papyrus fragments of the New Testament that date to about 200. There is a list of papyri in the UBS edition of the Greek New Testament (I have the third edition, corrected, from 1983)--it has 4 listed as dating from 200.
There were Church Fathers before 200 who quote from the books of the New Testament (even if there wasn't complete agreement on which books were inspired until later).
There were Gnostics in the second century--Eusebius mentions some of them in book 4 of his history of the Church (Basilides, Carpocrates)--he is very negative in his attitude towards them. So it is possible that the newly-discovered text could be a translation of something dating from the second century.