Well people might argue with me so don't tell, but I have found this method to be 85% accurate if not more. The spot on there face where the comb will be will begin to swell and turn a little more red at about the age yours are now. Both of your's look pretty flat and yellow to me so... I say...
Hey, Thanks! It might be to early to tell but right now they both look like hens! The one on top might be a rooster, but as of right now they both are looking pretty girly!