I search Google Images whenever I need help with terms. Searching "halo effect stereotype" gave me this answer that I'm rephrasing:
Stereotype= (1) you see somebody, (2) assign them to a broad group, (3) you assign attributes based upon group
Halo effect= (1) you see somebody, (2) you focus on one attribute about them, (3) you assign other attributes based upon previous attribute
(ex. I see a man/woman; they are a doctor; they must be smart, a good person, etc.)