I think the difference is, and I may be wrong...but those who purchased from Best Buy actually paid for their devices. Just as those who pre-ordered via Sprint.com actually paid for the full cost of their phones. Whereas those who purchased thru a Sprint store paid $50 so Sprint would hold one for them once they came in. Basically when the store finally does receive the device, you will get first dibs before the average Joe walks in to buy them. But those who paid the full $200 actually paid for an actual unit...so they get their first.
Thats just a guess though.
Money out of pocket for BB pre-order.......$0.