Observation period - There shouldn’t be a person record if there is no observation period. There is no overlapping periods
Payer plan period - is to represent the contractual relationship between a person and payer/sponsor/plan. This may be a subset of observation period. There may be overlapping periods in payer plan period table because a person may have a primary payer and secondary payer for the same time periods. There may be periods in observation period that are not in payer plan period - but not other way around. Periods in observation period, that are not in payer plan period indicates no contractual relationship.