aliasing explained

this is the best explanation i've found on the phenomenon known as "aliasing" aka "the reason digital sounds different than analog" aka "why the microkorg sounds fake as fuck." makes me wonder about the age old question: is there a difference between a DCO and a VCO (besides the fact that a VCO is less stable and drifts around)? is it the digital filter and amp stages that make virtual analog sound so shitty, or the oscillators?