Brainwashing is about a person or group giving people some ideas in attempt to change their value, belief and thoughts towards what the brainwasher wishes to accomplish.
This is unethical but rather commonplace.
Hypnosis has sometimes be misunderstood as brainwashing people.
Hypnosis is ethical and its aim is to help people attain what they want eg. eliminate a bad habit like nail biting. It is based on the consent of the hypnotized person rather than forcing the person do what he does not want to. There is no change in the person’s value, belief and thoughts before and after hypnosis.