stereotypes are a way to "put a label on someone" so therefore is a form of prejudice if you do not know the person
but only if you do not know the person or haven't met them.
putting a label on someone you know is not prejudice
prejudice is pre judging an individual before meeting them
so there are ways that stereotypes can differ from prejudice because <u><em>if you know the person, placing a label on them would not be prejudice.</em></u>