Hello @Hess Mir and thanks for reaching out. Both personal and work accounts are cloud accounts. The former are created in a single common tenant (https://account.microsoft.com/account) while the former in a custom Azure AD tenant. You can create personal accounts using any mail provided you own the email address. You can create work accounts of any domain (but not hotmail.com, outlook.com or other reserved domain names) provided you own the domain.
Personal accounts can be added as guest into Azure AD tenants and access SharePoint Online. They can also access the (free) personal version of Outlook (http://outlook.com/). Work accounts do not need to be added as guests to access SPO and can access the business version of Outlook (https://outlook.office.com/).
You can add work accounts to Windows following the instructions located in Add or remove accounts on your PC
-> Add people to a work or school PC.
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