Firstly, what are you making? Beer, cider, mead?
Secondly, why. Not asking to be a butt-head, literally asking what you are looking to get from each from the recipe?
Cinnamon: a little goes a long way. Some add to the boil, some in primary, others in secondary. Some use whole scrolls, others make a tincture and add it to primary, secondary or at packaging.
Brown sugar: I suggest against it. I hate giving anecdotal advice, but I have heard that brown sugar can add off flavors. The sugar ferments dry leaving the unfermentables. I've heard raw turbinado, palm or coconut leave more residual flavors.