What's the difference?

Is there any difference between alternative medicine and complementary medicine?
Are there any specific governing bodies?
Are there any practitioners of any 'alternatives' that aren't qualified vets? If so how does that work? I thought it was against the law for anyone other than a vet to treat dogs? I know for eg that GPs would get into trouble for treating a pet but a vet can technically treat people.
Are there any 'alternative' therapies that lay people can study and provide?
Jane Thomas, Reading