That is a bit confusing. In-cell uses the LCD pixel wiring, slightly reconfigured, to do touch sensing too - pretty much it does this in the blanking intervals. You can't do it during active refresh for obvious reasons (the wiring is being used.... and it's electrically noisy).

Given that in-cell basically gives you "free" touch sensing - well, in terms of number of layers of ITO and number of bits of LCD-quality glass you need at least - I've no idea what "touch on display" is supposed to offer in terms of advantages.

Unless, of course, it's just someone else's marketing term for in-cell...