B2B Direct connect
Using B2B direct connect only supports Microsoft Teams and the external organization must be in Entra ID.
If you or your clients utilize Teams as a collaboration tool, they may engage in partnerships with external organizations, external users are initially added as guest users before being granted access privileges to your Teams/Channels.
However, what if this is a long-term project, the other organization with which you are collaborating has numerous departments or users, or you work closely with a sister company that has a distinct tenancy but with which you share certain responsibilities? Enter the trust relationship for the Azure B2B direct connect. I expect the scope of this solution to broaden in the near future, although its current capabilities are relatively restricted to Microsoft teams.
One of the main advantages of utilizing Azure AD B2B direct connect is the ability to effortlessly include users from the trusted tenant in a shared Teams Channel; the addition is reflected in their Teams without requiring them to transfer organizations. Before proceeding, it is possible that B2B direct connect is not the optimal solution.
B2B Collobration:
B2B Collobration is not just restricted to Teams but for all Microsoft applications or your own applications (SaaS apps, custom-developed apps, etc.) including Microsoft portal and resouces
Collaborate with external users by letting them use their preferred identity to sign in to resources in your Microsoft Entra organization. Provides access to Microsoft applications or your own applications (SaaS apps, custom-developed apps, etc.).
By utilizing B2B collaboration, the visitor user can be invited to join a team. The guest user for the B2B collaboration logs in to the resource tenant using the email address that was employed to extend the invitation. The permissions granted to visitor users within the resource tenant govern their access. Neither can guest users view nor partake in any team-hosted channels.
