There are differences between an aviation grade AHRS and a tablet's built in sensors. First, the level of accuracy is not the same; an aviation AHRS is depending on very accurate solid state gyroscopes, where as tablets tend to use accelerometers. Second, an AHRS board includes very fast sampling using a dedicated processor to ensure accuracy, whereas a tablet tends to just report real time information and apps can sample and interpret as needed - so a big loss of resolution. Third, an AHRS is intentionally placed close to level and tablets can be in just about any orientation. The end result is tablets focus on the gravity vector, which is pretty much irrelevant in an airplane (in a coordinated turn the g-vector doesn't change).
It's possible to simulate the artificial horizon using tablet sensors, but the data must be combined with GPS information for any sort of accuracy. And it breaks down if you are getitng into unusual attitudes. An good aviation AHRS doesn't use GPS, it properly senses turns and banks, and doesn't get confused easily.
-Walter