What Is Difference Between Microsoft Outlook & Outlook Express?

Outlook Express is primarily an email client and newgroup reader.  It is the default email client supplied with Windows and comes free with Windows.  It has all the basic facilities you expect from an email client - multiple identities, creation of folders to categorise stored emails, and automated log-in and log-out.  But it is just an email client.

Outlook is a full-blown contact management system.  It enables you to store details on all your contacts, and to easily search and retrieve this data.  It is NOT free with Windows, it is purchased as part of the Microsoft Office suite of programs.  It uses the basic Outlook Express email engine as a part of its functionality.  Overall it is much more powerful than the Express version.  It is the sort of program a company would use to track its business contacts and their details for example. The average home user on the other hand is only likely to need to use Outlook Express, as the extra features in Outlook are all business orientated.  A home user is notliekly to categorise their friends for example, but a business will categorise their contacts. Outlook will store electronic business cards, while Express cannot.

Outlook exp comes with you're operating system, while as MS outlook comes with office package.

Outlook express as part of internet explorer and  with the part of Microsoft office.  Outlook has a host of features that Outlook
Express does not have, such as a calendar,
a task list, a journal, and automatic backup into
archive files.
Outlook also has a very powerful Junk Mail feature.
Outlook has message rules for both incoming
and outgoing mail, while Outlook Express can
only filter incoming.
Outlook Express was designed for use on a single
computer and so its message store and settings
cannot be stored on a server. Outlook however
was tailor-made for networks, and so its message
store can be on a central server that many
machines can access.

Outlook Express is a POP3- and IMAP-compatible mail client with a built-in newsreader. It is available with Internet Explorer for Windows (and is the newsreader in Outlook), or as a stand-alone client for Mac OS 8.1 to 9.x (but not Mac OS X). Outlook Express is much simpler to set up and use if you only need to read email and news. You can configure it to retrieve email from your account via POP or configure it as an IMAP client to access your mail on an IMAP mail server.

If you have an Exchange server account, you have an Exchange server mailbox, which can store your email directly on the server. When your email is stored in your Exchange server mailbox, you can get to your stored email messages from any computer. However, when you connect to the Exchange server using Outlook, with mail delivery directed to your personal folders, unread mail will be moved into the Inbox of your personal folders instead of being stored in your Exchange server mailbox.