Access management: Deals with permissions, privileges and controls unified access policies.
IAAA - Identification, Authentication, Authorization & Accounting
Identity management: Primarily focuses on the technical aspects of managing user identities, authentication, authorization
PAM - Privileged Access Management
Identity governance: Compliance, account life-cycle, policy-driven access management, entitlements and provisioning
IGA - Identity Governance and Administration
Directory services: Centralized and consolidated credential management and synchronization