While they might share some superficial similarities, like their "quills" (which are actually modified hairs) resembling bristles, porcupines and pigs are very different animals.
* Porcupines are rodents, belonging to the order Rodentia. They are related to other rodents like squirrels and rats.
* Pigs are even-toed ungulates, belonging to the order Artiodactyla. They are related to other hoofed animals like cows, sheep, and deer.
So, while they might look a bit similar from a distance, porcupines and pigs are actually very distantly related.