As far as i can tell, it's payment due at the time of order. No terms or open accounts. You can place the order, however it will not be released until payment is received via CC, ACH, MO, Check, Wire Transfer. Appears to be more of a order management service for repeat customers (businesses) who do volume GC purchases. You can designate seperate mailing destinations for individual receipt and control activation remotely for security purposes. Also, by being confirmed by their business department, you are then allowed to purchase large quantities of GCs without getting a visit from "the man" as you are designated as a legitimate purchaser and not a "undesireable" using them for illicit purposes.
I could also be totally offbase with my assessment 
FYI, this may not have always been the case as Walmart's business programs have changed over the years as evidenced by them no longer accepting applications for their revolving "Business" store card.