The openstreetmap.org search box uses a geocoding engine called Nominatim, which returns a ranked list of possible locations based on the search text. Brooklyn's OSM address data is pretty good, so Nominatim's able to use that, but it also falls back on the US Census Bureau's TIGER dataset for places where the OSM data is not as complete.

In this case, the top results are from OSM's data and the lower-ranked incorrect result shown here is from TIGER. (TIGER data can sometimes be of poor quality.)

You can see Nominatim's full debug output like this:
https://nominatim.openstreetmap.org/search.php?q=51+Bushwick+Avenue+Brooklyn&format=jsonv2&debug=1 