Publisher is a DTP with some web building capability. Expression is the
replacement for FrontPage and is specifically designed for web design,
editing, etc. Yes there certainly is a difference. If you only need a simple
static web site, then Publisher can do the job. If your ambitions and plans
for your site are more ambitious, then Expression is a much better choice.

No, you won't be able to "translate" a Publisher site to Expression. The
code is very different. Start over if you want to use Expression.

DavidF