YSK: If you make popcorn in a pot on the stove, the oil to use is ghee.
Why YSK: Popcorn fans often want a buttery flavor, but plain butter is a bad choice for popping popcorn in a pot, because the proteins and sugars smoke and burn around the same temperature where it's hot enough to pop the kernels.
Ghee, or Indian-style clarified butter, is butter that's been simmered and the milk solids (proteins and sugars) skimmed off. This leaves a clear yellow oil that doesn't smoke when it's heated and doesn't go rancid quickly, but has a distinct toasty butter flavor.
Vegetable oil is either flavorless or faintly bitter, and some high-temperature vegetable oils tend to start polymerizing (i.e. becoming plastic) when heated in small amounts. This is also not good for popcorn.
Good-quality popcorn popped in ghee reliably produces lots of "butterfly" popcorn with few unpopped "duds" and no scorched kernels or batches ruined by smoke.
I've always just used avocado oil. Sometimes coconut oil but that obviously leaves a faint hint of coconut that not everyone likes. I'll try ghee next time but I never heard of anyone trying to make pop corn with just butter in the pan. That sounds like a mistake folks only make once! lol
The makers of my commercial-grade popper recommend coconut oil. Like you, I am interested in trying ghee. It's good to just have a bottle of that stuff handy for lots of things.
They are pretty much the same thing. Clarified butter can be skimmed as soon as the milk solids begin to separate. Ghee is cooked until the solids become browned and settle to the bottom, giving it more of a nutty flavor.