Architecture? or Uban Planning?

ACDouglas wrote a pregnant email:

"As you yourself pointed out, your opinions are concerned principally with urban planning -- with "site plans," as you put it -- not with architecture...urban planning ought NOT to be the business of architects. The business of architects is architecture -- i.e., individual buildings or group of buildings, project by project. The business of urban planning should be left to, well, urban planners who have no business messing about with matters of art. That's the business of architects."

Beguiling concept except when you get down to particulars. One minor particular is how/where do you the draw the line between architecture and urban planning?

For example, consider The Three Rules (and please do consider them, either in long form--a 500k PDF or short form--a 45k PDF)...well, are those Rules urban planning rules? or architectural ones? Of course I think that they are both. They operate as architecural constraints for a specific building in order to create a piece of urbanism.

So I question whether there is a reasonable, practical method to separate "architecture" from "urban planning" along the lines suggested above. No?

UPDATE: Murphs weighs in sensibly on Architecture vs. Urban Planning.