AWS service for centrally managing multiple AWS accounts. Like having a corporate headquarters that manages all branch offices with consistent policies.
Large enterprises use AWS Organizations to apply security policies and manage billing across hundreds of AWS accounts.
All four provide hierarchical governance across multiple accounts/projects/compartments. AWS Organizations groups AWS accounts into organizational units (OUs) and applies guardrails via Service Control Policies (SCPs). Azure uses Management Groups with Azure Policy/RBAC; GCP uses Organization/Folder/Project with IAM and Organization Policies; OCI uses Tenancy/Compartments with IAM policies.