Arella Mae, I'll try not to get carried away (not one of my strengths), and I'll try to stick with stuff that's visible, considering that the purpose is for you to be able to tell the two big cats apart.
Faces
Cheetah face:
Leopard face:
Notice that dark lines that run down the cheetah's face, from the inside of each eye, down past the nose, and around the "cheeks." Leopards don't have those lines.
Spots
Leopard spots:
Cheetah spots:
Leopards have what are called open rosettes. Each spot is in fact a pattern that forms the spots. Cheetahs are just plain old polka dotted.
Picture in a tree. If you ever see a picture of a big spotted cat in a tree, it's not a cheetah. Cheetahs can't climb. They do not have retractable claws. They have claws like a dog's--out all the time. This helps them run faster.
Built for:
Cheetah--built for speed:
Everything about the cheetah's body is designed for speed. Small head, breaks the window like an arrow. Long legs. Light frame. Long tail serves as a rudder. Think of a cheetah as a Ferrari.
Leopard--built for power:
Shortish powerful legs. Thick muscled neck. These animals are enormously strong. They can carry prey heavier than they are up a tree. Very strong--like a tow truck.
One reason why they are built so differently is their style of hunting. Cheetahs run down their prey. Leopards will lie in wait and pounce. Different bodies, different purposes.
I'm gonna stop now. I may have a pop quiz when you're least expecting it.
