What is MS Outlook good for, and what's the difference between Outlook and Outlook Express?

Answer 1

Outlook express carries email. It is specifically to use for sending and receiving email.
Outlook is used for appointments, addresses (or contacts) task reminders, etc. And there is so much more you can do with Outlook. I advise you to take a class. I learned a lot about Outlook in a class provided by my employer.

Answer 2

Outlook is all-in-one, calendar, contacts, notes etc. Also its designed for corp emails

Express is just for emails and simple email contacts.