The Short Answer
Go to Udawalawe if you want to see animals. Go to Yala if you specifically want a leopard and can accept that you may not get one.
Udawalawe holds around 250 resident elephants in a park of 300 square kilometres with open grassland, so you see them, close, on almost every drive. There is no realistic scenario in which you spend three hours there and see no elephants.
Yala has the densest leopard population of any protected area on earth — roughly one leopard per square kilometre in Block 1. That is the draw and it is genuine. But density is not the same as visibility: the animals are in scrub, they move at dawn and dusk, and a sighting is a matter of luck and of how many jeeps are radioing each other. Plenty of visitors leave without one.
The second difference is the one nobody mentions in listings: crowds. Yala Block 1 in peak season can put a hundred jeeps in the same park, and a leopard sighting turns into a traffic jam. Udawalawe is quieter, and the experience is calmer for it.

Yala National Park Leopard Safari Day Trip from Ella
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