The MINT is a buffered, dual supply, Class-A biased, Jung multi-loop amplifier. This should mean better sound because of the higher output voltage, higher output current, and lower distortion. All of these features come at the expense of a higher voltage requirement, higher current draw, less battery running time, and a larger case size. Even though MINT pcb's are made by tangent, the soldering and casework is done by different people. There might be differences in build quality, the number and type of batteries used, and what type of case is used.
The Pocket Amp V2 is a single supply, low voltage, low current draw amplifier with a focus on being very portable. This probably means lower quality sound, but with the benefit of significantly longer battery life, a small case size, and it needs only two AA batteries. Since it's built by one person, you get consistent build quality and better product support.
Two totally different approaches to portable amp's.