I believe you have a pair. 1st one a pullet and second a cockerel. It is early for silkie, but with that comb growth on the second, my first impression is cockerel.
I'm seeing 2 cockerels at this age ... Pullets head feathers are like cotton balls while the Cockerels have "pointy" streamers. They really are too young to figure, at 8 - 12wks should be easier to tell.