It seems that almost everything these days that is somehow related to email has the word “Outlook” associated with it so the phrase “I’m using Outlook” can mean different things to different people.
This is just intended as a quick overview of the different references to Outlook
Outlook (the desktop client)
This is the program that can either be purchased separately or more commonly comes as part of the Microsoft Office suite regardless of what version is including the annual subscription option to one of the many flavours of Office 365. This is the complete version of Outlook that runs on your desktop. There is no equivalent “full version” of Outlook that runs on any mobile device. Tablets running Windows 8.1 run the same version of Outlook as a laptop.
There are a variety of different versions of the “Office Suite” whether going back to Office ‘2000 to Office ‘2013 (aka Office 365). The one version that does not and has never included Outlook in the suite of available programs is “Microsoft Office Home & Student”. Buying Office H&S will require purchasing Outlook separately if its required in the future.
There is only one version of Outlook whether it’s purchased separately or as part of an Office suite.
Outlook.com
Outlook.com is not an email client. It is a FREE email account provided by Microsoft which can be configured in any email desktop client as either POP, Imap, MAPI (via Outlook Hotmail Connector) or EAS (Outlook ‘2013). An Outlook.com account can be configured by ANY email desktop client that supports POP3 or Imap. There is no requirement to use the Outlook desktop client to access an Outlook.com email account. For limitations using an Outlook.com as an EAS account see “Understanding Email Protocols“
Outlook.com is now the official name for Hotmail and Live mail accounts. An Outlook.com is also associated when a Microsoft Live ID is created but there is no requirement to use that email account.
Early in 2014, Microsoft discontinued allowing the use of custom domain email addresses with it’s free Outlook.com account for newly created accounts but continues to support custom email domains that were already in existence.
Outlook – the Win 8/8.1 mail applet
The free mail applet that is available as part of WIndows 8/8.1 is a source of confusion for some since the word “Outlook” is used in the top left hand corner when the application is opened. It is a completely separate and distinct program Outlook (the desktop client). There are no functions provided that synchronize the accounts configured in this Mail applet with Outlook (the desktop client).
Outlook Web Apps (also known as Outlook Web Access)
OWA is the browser based web interface used to interact with an Exchange based email client either managed locally or via a hosted Exchange account providing basic functionality primarily used when there is no access via the Email Desktop Client.