First Officer reports departing PHX on the MAXXO 1 departure; only to be informed by ATC they should be flying the SJN 5 departure. The printed PDC had been correctly interpreted and the FMC had been correctly loaded.

Narrative

We departed Runway 26 on the MAXXO 1 and started our southwest turn when commanded by the FD; around 500 FT AGL. A few seconds later Tower asked us if we were flying runway heading. We said no were flying the MAXXO 1 as cleared. Tower information showed us on the SJN 5 departure and instructed us to fly runway heading. We complied. We; again; double checked our PDC and FMS. They were in agreement for the MAXXO 1. Tower told us MAXXO 1's had been shut down and wanted us to fly the SJN 5. They gave us radar vectors for a couple minutes then switched to departure control. PHX Departure cleared us to a fix on the SJN 5 and then was told to resume the SJN 5. We complied. Upon switching to next sector (PHX Departure still) we again verified our new routing as: SJN 5 SJN J74 IRW then flight plan route. We continued flight. It was routine from there on.I have the original PDC with me. It shows a REVISED SEGMENT *****MAXXO1 ACH-*************** and the FILED CLEARANCE: PHX CHEZZ2 DRYHT ***. DATE; FLIGHT NMBR; AIRCRAFT NUMBER AND TIME ARE ALL CORRECT. Don't know why ATC had something different. There was an aircraft swap; and a new release printed but this was the correct PDC as verified by both pilots. Routing was verified by both pilots. Confusion was quickly addressed without compromise to safety. No separation was lost. It doesn't make sense. If we had suspected a difference we could have verified routing with ATC. However; having a revised segment is not unusual.