While therapy dogs are required to undergo training and become certified, they work for people other than their handler and are not covered by laws such as the US Americans with Disabilities Act.
This training sets the foundations for the assistance dog to remain focused while working.
An assistance dog prospect will also go through obedience training to ensure they remain under control of the handler.
During this training, the assistance dog will learn to perform tasks that will aid their disabled handler.
The tasks that an assistance dog is trained to perform will differ based on the handler's disabilities and needs.