Why is the autoguiding port diagram in my telescope's manual different than the diagram for the NexGuide connection?

The differences are not really important.

Here is the diagram for the NexGuide pinout requirements:
NexGuide pinout

Here is the diagram for the autoguiding port on Celestron mounts (the mounts meet the so-called ST-4 standard):

Mount pinout

The differences in the directions of RA (left and right) and Dec (up and down) are unimportant, as they are usually recognized by the software or firmware used for the guiding. These directions can also be reversed by user choice in NexGuide and programs like PHD and MetaGuide.

The mount port can deliver 5V out of its pin 1 if it is needed by a guider plugged into it. Since the NexGuide has its own power supply, there is no connection (NC) on NexGuide’s pin 1.

 

 

Updated 12/3/13