Differences between "MS Account" and "Organizational Account" when sharing with external users

When i share a SharePoint site with external email address, and the user click on the invitation link they will get this screen:-

now my understanding is that the "Organizational Account" allow users to sign in to the site using their office 365 account, while the "MS Account" option allow them to login using their Hotmail account, and also also allow them to map their non-MS accounts such as yahoo,gmail, etc as MS account? is my assumption correct?

and if they want to login using the "MS Account" using their yahoo account or non-MS account, then they have to create a password for their mapped email? is my second assumption correct also?

Thanks

Thanks