What is the difference between mistaken and mistake?
A mistake is a noun
mistaken is an adverb usually modifying a state of being verb.
He made a mistake
In this sentence mistake is a noun the object of the action
He was mistaken in his actions.
In this sentence was mistaken is the complete predicate or verb.
Was is the main verb that expresses a state of being
mistaken is the adverb that modified and defines the state of being.
The state of being is that he made a mistake.
While mistake and mistaken are two different parts of speech they can be used to express the same or close to the same thought.