Microsoft two different logins for their services:
- Microsoft Account (former Live ID)
- work or school account (Azure AD)
Both are located in different directories. The Microsoft account is located in another user database at Microsoft, as a work or school account. Latter are located in a Azure AD, which is associated with a customer. Both account types are identified using the email address. Microsoft accounts are used for service like Skype, OneDrive, but also for the Microsoft Certified Professional portal. Work or school accounts are mainly used for Office 365 and Azure.
You can use your work email address for your Microsoft account, until someone creates an Azure AD, and a work or school account with the same email address is created. From this point, your login experience with the different Microsoft services will getting worse. The main problem is, that Microsoft tries to find the given account in one of their directories, and it seems that they prefer Azure AD. So the login will work, but the content of the user profile will be different, because it’s a different account.
This is a screenshot from the new login screen. As you can see, there is no way to choose if you wish to login with a work/ school or Microsoft account.
This is the old login experience, where you can choose between work/ school and Microsoft account.
Microsoft calls this an AzureAD and Microsoft account overlap, and they identified this as an issue. As a result, Microsoft denies the creation Microsoft accounts using a work or school email addresses, when the email domain is configured in Azure AD. Microsoft has published a blog post to address this issue: Cleaning up the #AzureAD and Microsoft account overlap
Because of this, you should avoid using your work email address for your personal Microsoft account. Even if this Microsoft account is linked to your MCP/ MCSE certifications. It is not a problem to use your personal Microsoft account, with your personal email address, for your certifications. And it is not a problem to link this account to a Microsoft partner account (as in my case).
Maybe it will be possible to merge Microsoft and work/ school accounts someday. There is an ongoing discussion about this since 2013 (Merge office365 and live accounts that use the same email address).
To remove your work or school email address from your personal Microsoft account, follow the instructions in this support artice (Rename your personal account).