A roast (no "pot" about it) is a piece of meat that is placed on a rack above the drippings. It usually is fatty enough and/or has a fat covered side that it will be moist and it is a more tender cut to begin with, not chuck or other part like the pot roast. I usually stud those with big slivers of garlic (pierce with a knife then shove the sliver into the meat along the knife blade), liberally salt and pepper, and then start them for a few minutes in a very hot oven, and reduce it to finish roasting. I think the rule of thumb I've used (haven't made one for a while) is 6 minutes a pound at 500, then turn the oven off and don't open the door for an hour and it finishes cooking.

SRS