Collecting or Hoarding?

[RHClarke]

I fancy myself as a HUP collector, but I could also be seen as a HUP hoarder. My observations:

Both categories obtain vehicles.
Both categories "save" some of said vehicles from oblivion.
Both categories involve considerable effort and cost.

I tend towards the collector category as this is my only real hobby, but my wife thinks otherwise.

By definition hoarding as a human behavior falls in to two main categories.
One type of hoarding is triggered as a response to perceived or predicted shortages of specific goods.
Compulsive hoarding, on the other hand, is a mental disorder marked by an obsessive need to acquire and keep things, even if the items are worthless, hazardous, or unsanitary.

OK, so my dear wife may have a point. So? What's the difference? Is there a set number of vehicles that make you a "collector"? How do you earn the "hoarder" sorbriquet?