The red-billed tropicbird can be differentiated from the other tropicbirds by its red bill in combination with its white tail streamers. The slightly smaller red-tailed tropicbird has red rather than white tail streamers, and the white-tailed tropicbird can be differentiated by its smaller size, black stripe along its upper wing coverts, and its yellow-orange bill. Juvenile red-billed tropicbirds have more heavily barred upper parts than juveniles of other species. In flight, the royal tern can be confused with the adult red-billed tropicbird but can be distinguished by the former's less direct flight pattern and its lack of tail streamers.