Both the Zoo and an animal sanctuary give protective asylum to animals and birds. However, the zoo keeps animals in captivity, within artificially created habitat, whereas the sanctuary provides home to animals in their natural habitat without captivity.
Additional Info: That is correct, but a Zoo is a park made to put the animals on display for the public, that is it 's purpose. It is an institution designed to exhibit living animals to the public in a park setting. While a Wild Life Sanctuary is a protected area reserved for animals to live a natural, undomesticated life without threat or intrusion by humans through hunting, trapping, etc. or otherwise disturbing their habitat, and protected lands. That guards the animals normal "wild" life.
A zoo is designed around the concept of housing, tending, and controlling wild animals safely using enclosures, including the large areas used as ranges, sometimes many acres for some species, while still maintaining the visitors ability to interact with all the different species at the zoo. Some zoos are charity organizations, and do not have to compete out right for consumers spending money, but many zoos are strictly profit driven business. The profit driven zoos are designed to cater more to what they feel customers want or desire for a day out. Many zoos focus on providing the general environment that animals would live in naturally, allowing them to behave as though under normal circumstances, but they must also incorporate the customer 's general needs, and provide viewing, teaching, and some direct interaction with most, if not all species in residence. A wildlife sanctuary isn 't concerned with the need to support itself. Usually a sanctuary is run by a non-profit organization, single individuals or some type of governmental group. The main priority is the safety of the animals, concerns for human comforts, and desires aren 't taken into account. Most wildlife sanctuaries are focused on providing protection for animals, and the land that is important to the well being and growth of a specific species population. They will try to protect the ecosystem to a degree, monitoring the species, using whatever method possible including, long range observation, while giving the species a protected area to live without human disturbance. Some of these sanctuaries, or protected areas have been used for the release of rehabilitated animals, or as the first stage release of animals in breeding programs. This can give animals the advantage of close monitoring during it 's first days of adjustment to living in the wild. Both zoos and wildlife sanctuaries don 't allow hunting, trapping, fishing, or harming animals in anyway. For more details, please see the sites listed below.