Cheetahs are the only big cats with solid spots. They also have stripes at the ends of their tails.
Servals also have solid spots but they are smaller cats and they are easy to identify because their ears are huge.
Leopards have rosettes of spots and their bodies are more compact and muscular.
King cheetahs are different.They actually have what appear to be large thick stripes. However they are rare ( most likely extinct in the wild) and they look like spotted cheetahs in every other way.