Azure Active Directory (in short – Azure AD) is a cloud identity provider service or Identity as a Service (IdaaS) provided by Microsoft. Its primary purpose is to provide authentication and authorization for applications in the cloud (SaaS apps).
Azure AD B2B
Now for Azure AD B2B (which of course stands for Business-to-Business). Is it a different version of Azure AD? No! It’s only one of its service features. It allows one organization to invite members from other organizations to share application access.
Azure AD B2C
Azure Active Directory (Azure AD) B2C: it is a separate service from Azure AD. Built on the same technology, but still… for different purposes. It’s an identity management service that enables you to customize and control how customers sign up, sign in, and manage their profiles when using your applications. Also it’s built to allow anyone to sign up as a user in a service with their email or social media provider like Facebook, Google or LinkedIn.