Psychics tune in to auras and your guides, higher self, angels, etc to help you get clarity about the path you're on, and to address areas of your life like career, relationships, health, etc.
A medium communicates with your deceased relatives to bring you validation that they are "alive" and well on the other side. Deceased relatives don't usually comment on health, career, relationshps, etc because they are not guides. They send love and special moment messages.
A medium is almost always a psychic, but a psychic may or may not be a medium.
Angels are totally different from guides.
Read this for more info:
Spirit Guides, Guardian Angels, and Archangels Defined