"Where we grow"- Sprawl as movement from the core to the fringe of a region.
"How we grow"- Sprawl as development oriented towards drivers as opposed to nondrivers.
Often, the two go together: a car-oriented development 20 miles from downtown is certainly "sprawl" by either definition. But a new urbanist development in an outer suburb (such as Celebration or Kentlands) is sprawl in the first sense ("Where") but not in the second ("How.") On the other hand, in car-oriented cities like Atlanta and Jacksonville, there are car-oriented neighborhoods built in the 1940s and 1950s- some as few as four or five miles from downtown. These places are sprawl in the second sense ("How") but not in the first ("Where").
Policymakers who wish to limit sprawl must adopt different policies to deal with each type of sprawl. Urban growth boundaries and farmland preservation limit suburban growth and thus affect "Where we grow" sprawl- but do nothing to affect "How we grow" sprawl. "How we grow" sprawl, by contrast, is not going to be affected by limitations on overall suburban growth. The most effective way to limit this type of sprawl is through density, diversity, and design- encouraging compact, mixed-use, pedestrian-oriented development in city and suburb alike.