It is still early. One looks to have a single comb, the other looks to have a rose comb. The one with the rose comb may be a male, but it should be easier to tell in a couple of weeks. I've been told it helps to wait until they are fully feathered to determine breed and gender. Their legs are awfully dark and feathered, which should help you narrow down breed. They could be crosses.
The rose comb chick is definitely a cockerel. Many chicks I have found are able to be sexed at around 4 weeks. There is an occasional difficult one and certain breeds are much trickier, but in general single combed and rose combed chicks are easier. A chick's comb may pink up slightly at 4 weeks but if ithe comb starts to grow and get pink/red then it's a boy. As for the first chick of yours it is looking like a girl at the moment.