What is the difference between guest access and external access in Microsoft Teams?

Guest access and external access in Microsoft Teams are two different ways to collaborate with people outside your organization. Here are the differences:

1. Guest Access:

   • Guest access allows you to add an individual user (regardless of domain) to a team where they can chat, join meetings, collaborate on documents, and more.
   • Guests have the same capabilities as team members, with some exceptions. They have access to team chats, meetings, and files, and can receive and respond to channel messages.
   • Guests must be invited using their Microsoft 365 or Office 365 work or school account. If the guest doesn’t have a Microsoft 365 or Office 365 account, they will be directed to create a free Microsoft account using their current corporate or consumer email address, such as Outlook.com or Gmail.

2. External Access (Federation):

   • External access gives access permission to an entire domain.
   • External users can call you through Teams, and you can call them.
   • External users can also participate in one-on-one chats, but they won't have access to teams or team resources.
   • External access is a way for Teams users from an entire external domain to find, call, chat, and set up meetings with you in Teams.
   • You can also give them permission to join meetings or to collaborate on documents.

In summary, guest access is about giving individual users access to specific teams and their resources, while external access is about allowing Teams users from other domains to find and collaborate with you in Teams.