[jrmg]

It can of course vary considerably by store, and I’ll happily spend time in both but, generally:

Second hand bookshops are curated actively - like, they’ll only stock desirable books. They’re owned and run, usually, by people who love books. The staff tend to be knowledgeable.

Charity book shops are much less curated - to the extent that some just stock whatever is donated (which, of course, is largely made up of books people don’t want), so they tend to have a large collection of random books of not as high quality. They’re run by volunteers - which generally means enthusiastic staff, but it does not mean knowledge about books.

[m463]

I wonder if #1 comes over and culls through #2

[bpshaver]

1000% yes, at least with the help of book scouts that cull #2 and sell what they find to #1 for ~40% of retail.

If you want a fun fictional take on this, John Dunning's Booked to Die is a biblio-mystery about a Denver detective / book-lover investigating the murder of a book scout within the 1980's Denver used bookstore scene.