Is an ESA dog an assistance dog, companion dog, therapy dog or service dog?
No!
ESA animals have no special training. An ESA dog is a pet to which humans have a particularly intense bond. The animal is important and has a special and individually supportive function for humans. Man realizes that he is better off when his animal is nearby. Humans and animals are a psychologically functioning team. An ESA animal should therefore not be separated from humans.
Assistance animals, therapy animals and accompanying animals, on the other hand, are specially trained animals (mostly dogs) that can deal precisely with the needs of the assigned human being. They are specially trained and educated. These animals have a legal framework in many countries that leaves no choice to a third party but to accept them. Appropriate animals must be accepted in the respective context.
ESAs, on the other hand, are emotionally oriented animals often without special training. They are just as important to the assigned person, but do not need to be legally allowed in certain defined situations (except USA).