Good Day!
The crankshaft harmonic balancer is installed on the end of the crank 1st. It has NO facility for V or serpentine belts.
The pulley is bolted to the front of the crankshaft harmonic balancer. It has V groove(s) or serpentine surface.
Both parts have two metal parts separated by rubber. The harmonic balancer has a thin bead of rubber between the inner & outer parts; the pulley has a really wide (> 1"?) rubber.
The confusion is that lots of folks (parts mfg's, parts outlets, etc) call these two parts all sorts of unclear names. The most common one I've run into is calling the pulley by the harmonic balancer name. I had a devil of a time getting the right parts from NAPA the last time.
Blessings!
82 6.2NA K15 4X4 pickup, 4spd man w/ OD, 335K+ "In Rust We Trust" (parked)
95 6.5TD 2500 4X4 pickup, Gear Vendors Aux. OD, > ¼ million miles - gone
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93 6.5TD 3500 4X4 1T crew cab LB pickup, 230k miles