*MPVI2 is the interface used with HP Tuners tuning software. You need a laptop to use it.
The major difference between the two is that the MPVI2 will require a Windows laptop to flash tunes and to datalog. The MPVI2 is merely an interface that is used with HP Tuners VCM Suite tuning software. They have plans to add a cell phone app with Bluetooth connectivity that will allow you to flash and switch tunes as well as monitor parameters like the nGauge, but they have not released any details regarding this nor a release date.
The nGauge is a stand-alone device that is able to load tunes and monitor/log without the need for a laptop. However, there is one major drawback to the nGauge, in that it is lacking many important datalogging parameters that we would need if you ever decided to add forced induction to your truck, but for a Naturally Aspirated truck the nGauge logging works great.