Generally speaking, you bake food in an oven, whereas a kiln is used for the production of ceramics, pottery, etc.

A kiln is also technically an oven, although in modern times (in western cultures) it has developed into becoming an oven especially for drying, firing. or baking anything at very high temperatures. it does not have to be only ceramics or pottery. It can be for a special hardening process or many industrial uses. The word comes from latin meaning (oven to cook ) and long ago people would have cooked in a kiln and called it a kiln/kil, that was made out of clay in a field. Today you can still cook in a kiln and people do this. You can even buy kilns for cooking. (See the link below). A field oven, an oven made from clay is what an ancient kiln would have looked like when kilns were used for cooking in England long ago. You will occasionally hear a few people say. "a firing oven" to refer to a kiln/oven used for a non cooking reason. OBVIOUSLY you do not want to cook food in the same ovens you FIRE pottery or for other industrial poisonous processes like hardening toxic metals. A kiln is often pronounced with a silent N as kil. A cooking kiln --> https://nmclay.com/informational-pages/kiln-cooking a field oven or kiln/kil --> https://www.youtube.com/watch?v=i0foHjPVbP4 <- like we humans used to use before especially making them for pottery only and then later for more modern uses only.

"Oven" is a very common, everyday word with a wide range of meanings. It commonly includes enclosed devices used to cook foods by heating them from all directions. Our kitchen stove contains burners on top, and an oven underneath. We also have a microwave oven. Pizza cannot be properly prepared in an ordinary home kitchen oven, it takes a special brick oven to cook it correctly. A kiln is a specialized kind of oven used to dry and harden (to "fire") ceramic pottery, and also in industrial processes. The temperatures are often in the range of 1,000°C.--much higher than those used to cook food. So, a kiln is a kind of oven, but not all ovens are kilns. If you talked about cooking food in a "kiln" people would laugh--it would burn it to a crisp. You can't roast a chicken in a kiln, and you can't fire a pot in a kitchen oven. As a footnote, I honestly believe that the "n" in kiln ought to be silent--the word ought to be pronounced exactly the same as "kill." However, pronouncing the "n" is now so common that it is probably better for me to give up and say "the pronunciation has changed" (or possibly even "I am wrong.")

As far as I know, a kiln is only used for firing pottery. Oven is a more general word, mainly used for cooking food.

Have a look here: https://dictionary.cambridge.org/dictionary/english/kiln