Therapy dogs must must pass the Canine Good Citizen (CGC) test and therapy dog certification test. While the training is thorough, it is less extensive than service dog training.
Therapy dogs visit hospitals, nursing homes, schools, libraries and other places to engage in “therapeutic contact.” That just means petting, spending time, and giving comfort and joy to people who may need it.
Therapy dogs generally work with their owners on a volunteer basis. They often wear vests or bandanas that identify them as therapy dogs.
Therapy dogs and their handlers have no special access rights under the ADA. They visit hospitals and other facilities by permission.