Various little parts were changed during the Hardbody's run.
Typically, the Pathfinder followed those changes.
It depends on what you are looking for parts for. Obviously, the rear coil springs on the Pathfinder will not work on the Hardbody.
The radios, door panels, and seats should fit with no problem. The gauge clusters will fit if both of them have the same kind of dash (square or round).
Engine parts? It depends what engine both have. VG30i or VG30e. The Pathfinder did not come with a 4 cylinder, so if you have a Z24i or KA24E the parts from a Pathfinder engine will not work.
Like I said, it depends on what parts you are looking for.
~Joe (not a mechanic!)
1994 Heavy Duty D21, Long Bed, 2WD, V6, 5-speed
Free Hardbody Service Manuals: http://www.nicoclub.com/FSM/Hardbody/
Trouble Codes for Nissan 1988-1995: http://nissanforum.org/nissan-forum/showthread.php?t=23202