Porcupines:
* Body: Large, round, and covered in sharp quills.
* Tail: Short and stubby, with quills.
* Head: Small, with a blunt snout and small ears.
* Legs: Short and sturdy.
* Size: Can grow up to 3 feet long and weigh up to 55 pounds.
Beavers:
* Body: Stocky, with a broad, flat tail.
* Tail: Large, flat, and paddle-shaped.
* Head: Large with small, rounded ears and prominent buck teeth.
* Legs: Short and powerful, with webbed hind feet.
* Size: Typically 2-4 feet long and weighing up to 65 pounds.
In short: Porcupines are spiky, while beavers are furry and have large, flat tails.