Who knows? And who's business is it other than the collector? But I can tell you that if you think your pile of guns isn't a collection, you're probably right.
Those who feel confident on imposing rules on us to define our collections are out of line. We do as we please, its in the Constitution. There are no set rules to define it, and those who attempt to do so are usually motivated by less than honorable motives.
Way back, 40 years ago I was getting married. My mother hated guns, and she hated my dad's guns, and mine. I was moving stuff out of the basement where Dad had graciously allowed us to store things, and from my room. One evening, out came the guns. My mother real disgustedly commented about me taking my gun collection. Worse, that maybe my new wife to be wouldn't allow them. Lucky for me, my future FIL was there helping. He commented that if she didn't allow them, maybe I wouldn't allow her to stay! It really shocked my mother. FIL was an NRA instructor, and he liked guns. Wife couldn't care less. She had to move all her sewing stuff. She was busy with her own things, too busy to try to impose her views on me. Oh, we're still married.
And the huge collection consisted of the family heirloom 45-70, my 22, and my 870. I could carry all my ammo in a single wood box. Things are different these days...
My mother was disgusted, so she felt freedom to characterize my guns as a collection, as if I'd dedicated my life up to that point in getting them. The reality is I've dedicated my life since then to the pursuit. I want to call my pile of S&Ws a collection, so they are. If that's OK with you, fine.