Azure B2B (Business-to-Business) and Entra ID Cross-Tenant Synchronization are both features related to managing identity and access across different organizations, but they serve different purposes and work in distinct ways. Here’s a breakdown of the differences:
1. Purpose:
- Azure B2B:
- Azure B2B allows organizations to share access to their resources (such as applications or services) with external users from other organizations. These external users are added as “guest” users in the inviting organization’s Entra ID (formerly Azure Active Directory) tenant.
- The primary use case is to enable collaboration between different organizations, where the guest users can use their existing credentials from their own organization’s directory to access the inviting organization’s resources.
- Entra ID Cross-Tenant Synchronization:
- Entra ID Cross-Tenant Synchronization is designed to synchronize users, groups, and other directory objects across multiple Entra ID tenants. It’s useful in scenarios where a user needs to be present in multiple tenants with similar or specific attributes.
- The primary use case is when there is a need to manage users across multiple Entra ID tenants, often within a single organization or closely affiliated organizations (like a parent company and its subsidiaries). This synchronization ensures consistency of identity data across different tenants.
2. User Experience:
- Azure B2B:
- External users (guests) sign in using their home organization’s credentials.
- They have a guest identity in the inviting tenant, which is separate from their identity in their home tenant.
- Access is usually to specific resources, like apps or files, and is often temporary or specific to a particular collaboration.
- Entra ID Cross-Tenant Synchronization:
- Users are synchronized into another tenant and appear as regular users in that tenant (not as guests).
- They can have a persistent presence in multiple tenants, with synchronized attributes like username, email, or group memberships.
- The user experience is seamless, as they may not even realize they are operating across different tenants.
3. Management:
- Azure B2B:
- Admins manage guest users by inviting them to their tenant and assigning appropriate access to resources.
- B2B users are typically managed within the context of access to specific resources or applications.
- Entra ID Cross-Tenant Synchronization:
- Admins set up and manage synchronization rules that dictate how users and groups are synchronized between tenants.
- Users are often managed centrally, and changes in the source tenant are automatically reflected in the target tenants based on the synchronization rules.
4. Use Cases:
- Azure B2B:
- Collaborating with external partners, vendors, or clients.
- Granting temporary access to external users for specific projects or resources.
- Example: An organization shares access to a SharePoint site with a partner company.
- Entra ID Cross-Tenant Synchronization:
- Maintaining a unified identity across multiple tenants for users within the same organization or closely affiliated organizations.
- Example: A large enterprise with multiple subsidiaries that each have their own Entra ID tenants synchronizes user identities across these tenants to allow seamless access to corporate resources.
5. Security:
- Azure B2B:
- Guest access is typically governed by Conditional Access policies, multi-factor authentication (MFA), and other security controls within the inviting tenant.
- The external users’ home directory policies (like password management) remain in their home tenant.
- Entra ID Cross-Tenant Synchronization:
- Security is centrally managed, and policies are applied uniformly across all synchronized tenants.
- The synchronized users are treated as regular users in the target tenant, and all applicable security policies are enforced.
Summary:
- Azure B2B is best for collaboration with external users who need access to specific resources in your tenant.
- Entra ID Cross-Tenant Synchronization is best for scenarios where users need to be consistently managed across multiple Entra ID tenants, usually within the same or closely related organizations.
