Outlook Express (which comes with the installation of the Windows operating system) is simply an eMail tool and newsreader, with minor contact/address book capability.
Outlook (as what comes in Microsoft Office) is an eMail tool (no newsreader), a pretty capable contact and address book manager, a calendar tool, a to-do list manager, an appointment book, and a journal (which date manages which Office files you have created over time) - although almost nobody ever uses it as such, and maybe a couple of other things.
The two are similar in name only. The files that they use and create are totally different from each other. There is no easy way of easily transporting one set of information or list of contacts from one to the other (I believe there are share/freeware tools that do help). But Microsoft certainly doesn't help.
I am not going to argue the advantages of one over the other, nor argue the advantages of some other tool over what MS supplies us - and there are some really great share/freeware ones out there too.
Just have fun, and good luck with whatever you do use.
i have just installed microsoft office and seen outlook email client. whats the big difference between this and outlook express? or is there really no difference?