I was wondering if the passenger seat cover for the sides of the seat (commonly worn), is the same part # as the driver seat. If not can someone tell me what the difference between the two parts is, and if they are interchangeable?

 

They won't fit perfectly without extra padding.
The two seat bottoms are cut different due to different angles. So, no, the part numbers will be different.

I know for a fact the 'extra' skin you have on the drivers inner side and back inner can be filled with more foam/filler.

Raj