As referenced by Key HIPAA Privacy Principles...
Treatment means the provision, coordination, or management of health care and related services by one or more health care providers, including the coordination or management of health care by a health care provider with a third party; consultation between health care providers relating to a patient; or the referral of a patient for health care from one health care provider to another.
Payment means the activities undertaken by a health plan to obtain premiums or to determine or fulfill its responsibility for coverage and provision of benefits under the health plan; or a covered health care provider or health plan to obtain or provide reimbursement for the provision of health care.
Health care operations means any of the following activities; conducting quality assessment and improvement activities; reviewing the competence or qualifications of health care professionals; conducting or arranging for medical review, legal services, and auditing functions, including fraud and abuse detection and compliance programs; business planning and development; business management and general administrative activities.
Workforce means employees, volunteers, trainees, and other persons whose conduct, in the performance of work for a HIPAA-covered entity is under the direct control of such entity.