What's the difference? Is the distinction useful? Relevant? Particularly in terms of site plan/urban form/architecure etc etc?
My suspicion is the answer is "No" but I am curious to hear others' reactions.
The issue arises because of David Brooks' recent sales piece (for his book) titled Take a Ride to Exurbia in which he sets the stage:
People in established suburbs are moving out to vast sprawling exurbs that have broken free of the gravitational pull of the cities and now exist in their own world far beyond.
Ninety percent of the office space built in America in the 1990's was built in suburbia, usually in low office parks along the interstates. Now you have a tribe of people who not only don't work in cities, they don't commute to cities or go to the movies in cities or have any contact with urban life. You have these huge, sprawling communities with no center. Mesa, Ariz., for example, has more people than St. Louis or Minneapolis.
That may very well be true and of significance socially and politically. But from my observation, these exurbs have the same spatial form as do suburbs i.e. go look at where they park the car ib both suburbs and exurbs and they are the same. Now it's possible (and perhaps politically significant) that exurbanites have even less sense of what a pedestrian-oriented city is like than do suburbanites. But I don't think it would be by much.
Brooks, btw, doesn't use the word exurb in its original meaning in which it was simply a "region lying beyond the suburbs of a city, especially one inhabited principally by wealthy people." (American Heritage Dictionary) I first heard it in the 1950s (when it was invented by A.C. Spectorsky for his book The Exurbanites) to describe the wealthy areas of northern Westchester, Putnam and even Dutchess counties. These areas did indeed contain (and of course there wasn't much else then) traditional "main street" towns. Lovely towns, in fact. So it's a slightly annoying surprise for me to hear the term contorted. But I guess that is the way language evolves.