Does sprinkling salt on top of brownies give the same result as putting it in the batter?
Sprinkling salt on top won't have the same effect as mixing it in the batter, you'll get a big salt hit all at once and then nothing in the brownie itself which I wouldn't expect to be very pleasant. 

Some recipes withhold some of the salt from the brownie and put it in a sauce for the top like a salted caramel drizzle. This works because it's not pure salt on the top and there's still salt in the batter.