Why Discrepancies in the Gospels?
Why is the call of Andrew and Peter so different in John and Marks's Gospels?
The Gospels usually present variations on the same events. This increases rather than undermines their credibility. The accounts in the gospels of Matthew, Mark, and Luke are all very much in line with the quality of each Gospel. The same is true of St John's Gospel. There are so many elements that go in to the apostles' initial knowledge of and contact with the Savior, and the role of St John the Baptist was key among many of the first followers of Christ as they began to understand that hHe was indeed the messiah whose immediate coming they professed. Thus the differences, not discrepancies.