Enterprise architecture and business architecture

At the Melbourne BA conference I was asked to sit on a panel discussing what the differences and similarities of these two roles are.  I am not an architect and have not been one in anyprevious career.  So I wan't neccessarily prepared, and left that dscussion a little disapointed with where it went.
The discussion itself got stuck on how the Zachman framework is a full architectural framework that gos beyond technology.  Yep.  Okay, what next?
I'll throw up a few of my (still unprepared) thoughts here and see what comments I get.

• Architecture is about designing in future capability, not delivering it
• The differnece between enterprise architecture and business architecture is only a matter of terminology.  Or is it?  Mabe the business architure is less focused on the technical?
• If you put up an architecture it becomes the baseline for change, and variations from it have to be justified (to some degree)
• This means archicture should be an ongoing role and should generallly be flexible and open enough to accomodate new ideas
• Like anything, context matters a lot
• BAs are great candidates for architecture roles as they evolve through technology and business design
• Why doens't architecture drive more business cases?

That last point is one I am curious about from a project perspective.  If architecture is about building capability, surely it should be able to justify investment.  Why is it that (technology) architectural elements are usually only implemented as constraints on projects?