An aviary is much larger than a cage and is kept outside. They often resemble sheds with mesh sides. Most are large enough for a person to walk into. Example of an aviary from Daz, BBC member: Journey of Daz's Aviary

Cages are smaller and generally not tough enough to stand up to wind and rain and are therefore not suitable to be kept outdoors. Click to see Example of Cages from our Members AND Cage Setups