Sometimes I'll reheat some puff pastry wrapped items on a metal pizza tray (one of the ones with regular series of holes punched in it) as it helps with the keeping a crispier texture on the base.
This doesn't mean that my chicken and mushroom puffy has transubstantiated into pizza.
Similarly, cooking potatoes in what you call a roasting tin, or calling the meal a Sunday roast, isn't the definition of roasting any more than it's the definition of Sunday.
The distinction I draw is that roasting involves fire, baking does not.
The rest of the responses in this thread variously assert that the distinction:
- depends on temperature - there's a threshold above which you are now roasting not baking. This probably has roots in the cook by open flame / fire etymology, given that's usually warmer and harder to control accurately. (I will occasionally do a slow cook 'the next day' in my pizza oven using residual heat, and resurrect a small fire for the final smoking & crisping stage - though I am delighted to report that I have never pondered whether I'm then serving baked or roasted food.)
- depends on whether you peel your potatoes, which I'm struggling to reconcile given a) how does this distinction apply for non-potato and/or non-peelable foods, and b) if you peeled only half your potato and then cooked the whole thing - do you now possess a frankenstein potato, half roasted, half baked?
- depends whether the potatoes are cut - evidently once they are cut they can no longer be baked, only roasted. This is obviously at odds with the temperature crowd, and might (or might not) contradict the peeling-defines-state crowd too. They can work it out between themselves.
Anyway, I've had cooked potatoes in all kinds of forms, and I'm quite happy if people have their own local definitions for the two adjectives - so long as they're happy that I have mine.