Click here and all shall be revealed.
My first reaction was, they're basically the same gpu. So, in a nutshell, they're virtually identical. The MSI is overclocked a little more, but the cooler on the Gigabyte is better. You can make up the OC on the Gigabyte, you can't really make up the cooling difference. Get the Gigabyte. Or you could go with whichever one's cheaper.