We're splitting hairs here, it's only a word game to argue about whether it's a "sample" or not if the data has been procedurally generated rather than recorded. Anyway what if it was synthesised on another computer and sampled onto the Amiga? I can see no point in this line of argument.
The Amiga's sound generation is purely digital up until the DAC. It is not possible to generate any analogue wave. That's all that matters. Of course, square waves are easy.
But I gather some emulators and mod players "interpolate" the samples, reducing aliasing and giving what is in theory a higher-quality sound, but losing something in the translation.
In addition, Paula doesn't run at the 44.1kHz that a modern sound card resamples everything to, so there is bound to be a difference. Perhaps this is noticeable?