Well, I'll take a risk and dip my toe into these waters...It seems to me that projection is something that an individual may participate in alone. Projective Identification is more of a dance that requires the cooperation of at least two people -- one of whom is projecting emotion that is not felt or owned onto the "environment" and one who is confluent or "overidentified with the environment." The projector offers an invitation to identify with his/her unowned psychic content and the confluent one accepts.