both pullets.
at this age, a leghorn male would be showing obvious sickles(long curved roo tail feathers) and lots of super shiny and pointy feathers on neck and some starting to grow on back. Also their comb and wattles usually are thicker- and MUCH bigger than their sisters. Pretty common for leghorn cockerels to start showing very early comb growth- starting at two-four weeks.
The second bird does have a bigger comb but it is very thin plus no sickles or roo feathering.
Leghorn comb size varies a LOT. in some lines the combs are small on hens, in others they are much bigger. If you have pullets from each of those lines it would seem the ones from the latter are boys if compared to former. But put males in the mix, the difference is way obvious.