Thanks for the explanation! Perhaps the BD is also sort of like a counter to the Badlands, which is more expensive.Base and BD (non-SAS) are the two retro-look Broncos. Old style grill, old-style headlights, and traditional steel wheels.
Big Bend and OBX are the modern-look Broncos, with modern amenities and very modern-looking grills.
Badlands and Wildtrak are the performance Broncos, with "tough-looking" grills.