Collecting vs. accumulating vs. hoarding.
Well there is the technical definition:
https://www.psychologytoday.co.....-collector
But for me there is a subjectivity in the gray zones, where someone might not get or meet the markers for a clinical diagnosis, but it might cause significant family friction over mess/clutter, money spent, and/or use of space.
The main hoarder tendencies I've noticed are:
Persistent difficulty discarding or parting with personal possessions, regardless of their actual value. Extreme anxiety associated with this, almost like a loss of self or memory. The symptoms lead to extreme cluttering of the home or workplace. Rendering living spaces unusable? That's a sliding scale to my mind. Does it count if it takes someone a hour to find something even though they have bought that object multiple times in the past, if items are often misplaced, if areas such as beds and tables are unusable for months at a time?
Subjectively I think of collecting as containing an element of careful display and protection of, and pride in items. There might be friction because of money, time, use of space, but there usually isn't clutter or chaos.
I think of over accumulation as things designed for use, not display or cataloging, but there is a strong disconnect between the amount of stuff and use intended. For clothes it might be far too many 'everyday' clothes to wear within a calendar year, and significant numbers of items that need repair or alteration to be usable. For cookbooks or something it might be having bookshelves full, and boxes full of mixed up recipes cut from magazines and newspapers, but only cooking once a month. Same for project supplies -- significant numbers of half-finished projects and the materials for them, but months or years between working on them, and haphazard storage or monopolization of shared spaces for them.
I think there is definitely a lot of subjectivity and one person's mess is another person's 'homey'. For me I think the line that gets crossed is when one's stuff becomes a burden on other family members, and other people have to intervene regularly for cleaning, organizing, sorting, attempting to cull, etc. -- because it's beyond the desire or abilities of the person accumulating.