A cloud-based identity and access management service for securing user authentication and resource access
@Mario Scott (International Supplier), Thanks for posting in Q&A. Based on my researching, Azure AD registered is for non-corporate ("bring your own device") scenarios. These registered devices are signed in to via a local account. Azure AD joined is for corporate owned devices. It works only for Windows computers. The main difference you will notice is that you will have to login to the device using your Azure AD (work/school) account.
Currently, the names have been changed and now they are called "Microsoft Entra Register" and "Microsoft Entra Joined". We can see more details in the following link:
Hope the above information can help.
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