A relationship between an individual represented by a Person Account and another individual Contact is modeled through a Contact-Contact Relationship, with a Reciprocal Role describing the semantic meaning of that relationship.
A Person Account combines Account and Contact characteristics, but Salesforce maintains an underlying Contact identity for relationship modeling. Contact-Contact Relationship is specifically the structure used to represent a relationship between two individual contacts. Reciprocal roles define the complementary meanings of the two sides of a relationship—for example, Parent and Child or Client and Attorney.
Financial Services relationship visualization also depends on Contact-Contact Relationship and reciprocal role data when displaying person-to-person relationships in relationship components such as Actionable Relationship Center.
Account-Account Relationship is intended to relate two business-account entities, such as a household and a company or two businesses. Account-Contact Relationship is used primarily for relationships between a person and a business or group, for example household membership or an employment relationship.
Here, both ends represent people: the client is a Person Account with an underlying Contact, and the business contact is another Contact. Consequently, Contact-Contact Relationship holds the relationship record and the Reciprocal Role defines its meaning and inverse relationship.
