(Author here) IIUC you're saying that 707133f-a should be at 5th Ave & 9th Street, not 5th Ave & Union Street? Can you say more about why? The text on the back of the first image says "Union St. Station, 5th Ave," which is how it winds up at there. On the other hand, the NYPL page[1] titles the image "Union St. - 18th St."
(I briefly got excited that there might be a street sign _in_ the photo, but if you zoom way in it says "DENTIST")
+1 to 1940s.nyc. Very different photos — those are were taken for tax assessment, the ones on OldNYC were taken to document the city as it changed. The photographer had an arrangement where he'd get tips from demolition crews, and go shoot buildings before they were gone forever.
[1]: https://digitalcollections.nypl.org/items/5a5e06a0-c539-012f...