Pulling information from XML 3.0 API’s that contain N473UA sometimes say its a A319 and sometimes A320. I believe the correct AC type is A320. For example i searched “N473UA” in FlightInfoStatus.
This can sometimes occur if an advance flight plan filing indicates an incorrect aircraft type, it is normally corrected at or before departure time.
Specific type data for each flight is pretty unreliable for many airlines; if accuracy is important to you, consider setting up your own local database to correct the types based on tail numbers - it’d be nice if FlightAware could do it on their end too, but, I believe they’re just passing along what the airlines provide.