Hi jb
In my experience, all three, Veg Ghee, Animal Ghee and Veg Oil are used in BIR cooking.
Standard curries = Veg Oil, Special Curries = Ghee. Certain preparations = Ghee.
The stove top ghee tin will usually have Veg Oil in it.
The Tandoori Chef will have a tin or container of Animal Ghee, next to the tandor, to baste the Tandoori meats etc.
Animal Ghee completes a good Tikka Chicken.
cheers Chewy