What is the difference between warm-blooded and cold-blooded animals?

I know that warm blooded animals have self regulated temperature, higher stamina and require more food, whereas cold blooded animal's temperature is more reliant on their environment, theyre faster in short bursts and require less food. All of this, I know from science class. What I can't seem to find however is the workings of what makes them different. What I mean is, if a leopard and an crocodile each eat half of the same gazelle, the leopard processes it one way, the crocodile another. What causes this? What is inside the leopard, and by extension, a human that makes it able to generate heat and the crocodile cannot?