Psychological kin believe that their kintype is because of something happening in their brain.

Spiritual fictionkin believe that their kintype is because of real actual literal magic/ occult/ spiritual reasons.

Psychological kin generally don’t believe that souls, magic, alternate universes etc exist. They believe their kintype is similar to being non-neurotypical or due to a mental disorder.

Spiritual fictionkin believe that souls, magic, alternate universe etc do exist and are the reason for their kintype. (The exact specific beliefs are different for each fictionkin).