Speaking as a librarian, I was thrilled to see that these terms exist; I missed them initially, somehow.

To me, the {paq nojwI' qach} is the literal building housing the books and the staff, while the {tum} refers to the entity more abstractly. If you said, "I'll check the Library and see if they have that" and you used your phone app or the on-line catalog, it would be the {tum} you are accessing, but not the {qach}. If you are talking about visiting the library, I don't see much difference. I also don't see how {tum} implies "public", but that's how it's glossed, so be it.

BTW, I would qualify {De' QulwI'} as not just "librarian", but specifically "research librarian". In fact, as the term stands, it could refer to anyone in the data analysis or research field. {paq nojwI'} is much more appropriate for what I do all day.

ter'eS