Why does Aperture show the wrong street address for manually geotagged photos?

Aperture may not be resolving the full street address you entered. If it only recognizes a broader location such as the city or state, it can place the photo at a generalized point within that area, which may be nearby but not the correct street. That would explain why the result is off by a couple of miles.

Based on the available information, this looks more like an address-recognition or reverse-geocoding limitation in Aperture than a problem with the photo itself. A practical fix is to verify that the photo has the exact coordinates or a fully recognized location entry, rather than relying on a partial address match. If iPhoto shows the correct address, compare how the location is stored there versus in Aperture.