Not really a fair comparison, (1) Ether has a finite supply and they have not decided how many coins they will print (it is "an area of active research" ), and (2) they gave themselves a bunch of coins on day zero ("12 Million.. were created to the development fund, most of it going to early contributors..") and (3) they crowdsaled the rest of it on day 1... Grin isn't doing any of these things.

(quotes from https://www.ethereum.org/ether )