# Why can different technology transpile the quantum gate to different representations?

I saw that qiskit was just incorporated in a trapped ion device.

I transpiled my circuit to 2 backends: ibm superconducting device and aqt trapped ion device. I noticed that for ibm, the $$X$$ gate is transpiled into $$U_3(\pi,0,\pi)$$, whereas for aqt it is $$R_x(-\pi)$$.

Since both objectives of them are to take $$0$$ to $$1$$, why do they use a different quantum gate to do that?

By the way, for the aqt device, $$H$$ gate $$= R_y(\pi/2)R_x(\pi)$$. I was wondering, why are the two representations equal?