Frankly, you should just ask your manager what the comp change, if any, would be if you switched roles. This is a normal question in all but the most dysfunctional companies.
Why there’s so much taboo/avoidance of talking about money I have no idea, but if you need some information to contemplate a career change in our company, I’ll do my best to get it for you.
I'm guessing it is done that way so there is little room for favouritism and/or nepotism.