Same interface as an SD card, but better firmware and probably higher quality flash. SD cards are really aggressively cost-cut, often coming in than less than the price of raw flash of the same capacity.

As someone who has also worked with fleets of devices (R.Pi-based and others) working off SD-cards, I can confirm what jon-wood is saying. For some reason SD cards fail at a much higher rate than eMMC flash chips in traditional SMT packages.

It is, and it is better because it probably has better chips, but it will die, and brick RPi in the future.