The big difference is basically that a moka pot only passes the water through the coffee once under considerable pressure, whereas a percolator does it repeatedly without pressure. A moka pot gets you something pretty similar to an espresso (though not the same, as the pressure is still far lower)

That said, if you are using a percolator and enjoy it, that's what counts. I think the Italians are pretty good at coffee but it's always going to be a personal preference deal