As a piper, I think I can help explain some of this.

In some ways, the 'piper' designation just makes it easier for some sellers to market their wares (online searches, etc.). They're also being marketed with the aim of providing group discounts and/or bulk rate discounts to pipe bands or groups (Scottish/Burns Societies) wanting a uniform look. In many cases, it's a military style look that's being marketed (think of the stereotypical 'piper' in "full regalia" - Black Watch or Scots Guards, for example).

The "piper" products are often mass-produced, so the quality might not be as good as a custom order or higher-priced item. This will vary from item to item and vendor to vendor.

As far as "piper hose", in my experience they're designed to have a 'popcorn' look to the tops when they're folded over, and often can be folded over three or four times to give them that bulky look that is common in the military pipe bands.

A "piper sporran" may be one of the long horsehair sporrans, either white with black tassels or black with white tassels, both styles with a silver (or a white metal - chrome or polished nickel) cantle. That's generally considered a military style in the pipe band world, and most competing pipe bands these days prefer just plain leather sporrans.

A "pipers plaid" is similar to a drummer's plaid (and is probably them same thing, just worn by a different instrumentalist - I don't wear one, so I don't know for sure). It gets wrapped around the body, pleated across the chest, attached to the shoulder by a brooch, and hung loose off the back. Also a military style look.

A "piper's jacket" is probably a military-style jacket which buttons up the front, with shells at the shoulders (fancy braid following the curve of the seam front-to-back, projecting out from the shoulder), with 'tashes' or 'Inverness flaps' at the front which fall below the beltline. Often, a belt is worn over the jacket to help emphasize this.

Hope that clears things up somewhat.