Except outlook is the app you install on android or iOS to access your Outlook.com personal email, which is really hotmail, but not to be confused with outlook web access, which is the web interface to exchange’s mail. There’s also the outlook that’s part of office 365 for windows, which is “the business one”, except it is also in the office 365 personal edition, which you are not allowed to use for business, and that outlook is a completely different app from the outlook in office 365 for mac.

But the mail client on windows is not outlook, that’s just windows mail.