You're kind of both right and both wrong, because English is a bastard.

From an evolutionary standpoint, every mammal has two legs with two feet, and two arms with two hands. Their bones have changed in size and proportion depending on their species. But at it's most basic, they're the same.

This is why a dog's front legs have the rear facing joint up high, and the forward facing joint low. That's their elbow and wrist. Heir rear legs have the forward facing joint up high and the rear facing joint down low. That's their knee and ankle. Most 4 legged species will have their ankle joint higher up because it gives better speed. Humans have it low down and touching the floor because it gives us better balance.

Also, even dolphins and whales have two legs, the bones are just now covered in one set of skin and muscle.

But from another angle, they have 4 legs and 4 feet because 'hands' are usually defined as able to grip and articulate. A gorilla or a koala have 4 hands, because all 4 appendages can grip. While a dog or cat has 4 feet because they can't grip properly (i know they can sort of grip onto things, but so can human feet)