There's not much difference. To me, a "skillet" is make of thick, heavy cast iron, and has only a very shallow raised lip around the edge. You can use it for frying something that lies flat, like bacon or pancakes. A "frying pan" is often made of thinner metal, and is maybe 5 cm high around the edge, and can be used for cooking thick things, like pieces of chicken mixed with rice and onions.

A skillet has slanted or curved edges. It is better for stirfry cooking, tossing and flipping food. A pan has straight sides. With more surface area, it is good for frying meat. Hope this helps

Or in New Zealand

FYI we do not use the term 'skillet' in the UK.

They are more or less the same. I think of a frying pan as being a little bit deeper than a skillet. But read this... https://jovinacooksitalian.com/2014/03/10/easy-skillet-dinners/