Why are these methods returning different network interfaces?

Question

I've tried two different ways to return a list of network interfaces in OS X:

SCNetworkInterfaceCopyAll()

and the other way was to grab everything in the dynamic store key "Setup:/Network/Service/.*/Interface" and then return the interfaces that have a kSCPropNetInterfaceDeviceName key.

Each way returns slightly different interfaces. SCNetworkInterfaceCopyAll() returns the bluetooth modem, while the dynamic store does not. The dynamic store way returns a 3G card interface that I haven't plugged in months. I tried removing the kSCPropNetInterfaceDeviceName check, but still no bluetooth interface.