Many times when you use Microsoft Office programs online, or even when you want to sign on to Microsoft’s OneDrive cloud service, you will be asked to sign in with your Microsoft Account. So what does a Microsoft Account actually mean?
If you have an account for Hotmail, Xbox Live, Windows Phone, OneDrive, Outlook.com, Skype (the new, migrated accounts), or even a Windows (not the local Windows account), then you already have a Microsoft Account!
At the most basic level, you can sign in with your free Microsoft Account to access a whole lot of services. For example, if you sign in to OneDrive, you get access to a basic level of viewing and editing Office files within the program.
Many times, people get confused between Microsoft Accounts and Microsoft 365 subscriptions.
Firstly, basic Microsoft 365 subscriptions are also signed in via your Microsoft Account. Or you may have a greater level @on.microsoft.com email address that provides access to higher-level enterprise subscriptions for Microsoft 365. Whichever Microsoft 365 level you may be at, using those credentials unlocks the entire program on desktops, tablets, and phones.
So really speaking, all Microsoft 365 subscriptions are Microsoft Accounts, but not all Microsoft Accounts are Microsoft 365 subscriptions!