Service dogs and therapy dogs are not the same thing. Service dogs are often a specific breed, paired with a person with a disability, often go through very specific training, and aid people with a large variety of everyday or specific tasks. Service dogs are usually seen as working dogs, not pets.
Therapy dogs come in all shapes and sizes and are often there to provide comfort, emotional support, affection, and entertainment in places such as schools, nursing homes, prisons, and hospitals. These dogs often work with children with learning difficulties or disabilities. These dogs also work with people experiencing or suffering from the lasting effects of accidents, stress, crimes, and natural disasters or extreme situations.
Therapy dogs are not service dogs. Service dogs are protected in the United States by the ADA (Americans with disabilities Act); but Therapy dogs are not. This means public areas or public institutions may prohibit or limit access to a therapy dog. Training for therapy dogs varies, but it is a lot less rigorous than that of service dogs.