I don't know if Outlook can be downloaded as a free program, but both
programs will reside on your computer without conflict. Outlook Express is
part of Internet Explorer, and cannot be removed or else IE will not work.

Outlook isn't a free product but can be bought in stores or is bundled with
some PDA's.

Note that Outlook is a completely different program than Outlook Express;
it's not an upgrade or "full version" compared to Outlook Express.

Outlook Express is part of Internet Explorer while Outlook is part of
Microsoft Office.