The main differences lie in their size, tail, temperament, and barking habits. Cardigan Welsh Corgis are slightly bigger and heavier, have a long tail, and tend to be more reserved, serious, with stronger herding and guarding instincts, resulting in more barking. Pembroke Welsh Corgis are smaller, usually have a docked or short tail, and are more social, playful, and bouncy with less barking overall.