The rules and roles differ for service dogs, therapy dogs, and emotional support animals (ESA). Each type of dog has a different skill set, temperament, and rights or limitations to access public spaces.
Service dogs are trained to perform a task or tasks for an individual to help mitigate their disability. Service dogs accompany their handler in public where pets are not permitted.
Therapy dogs are trained to give comfort to persons they visit. Therapy dogs are invited into facilities for therapy for therapy dog visits. Reading groups, family courts, nursing homes, and hospitals are typical visits for a trained therapy dog.
Emotional Support Animals (ESA's) do not require training and may be permitted to live in housing where pets are not permitted. An ESA can be any animal that you feel provides comfort in your home. ESA's are not permitted on airline flights or in public spaces.