Ask HN: Mobile Card Swipe Solutions : Difference?

How are Square and a number of white-labeled incarnations of Roam Data differentiated? I read Roam Data's blog post about the difference in hardware-level encryption ( http://blog.roamdata.com/roam-datas-secure-solution-averts-square-like-attacks-on-its-customers-and-partners/ ), but then, what else is the differentiator?