What did the Jerusalem apostles know about Jesus compared to what Paul knew?
The Jerusalem apostles knew Jesus in the flesh and during the forty days after His resurrection, but they had no comprehension of the revelations concerning the Ascended Lord. Paul, by contrast, received all his revelations from the Ascended Lord in glory, so those apostles added nothing to him.
Les explains that these same apostles, who seemed to be somewhat, added nothing to Paul. They no longer had the preeminence and authority they had enjoyed in the earthly ministry and early Acts; it was slipping away. In God's view, Peter was no greater than anyone else, for God accepts no man's person. They knew Jesus in the flesh, and they knew Him during the forty days after His resurrection, but they knew nothing of the Ascended Lord. Paul, however, received all his revelations from the Ascended Lord in glory, which is why their conference added nothing to him.