A pullet is a female chicken under a year of age, and a cockerel is a male chicken under a year of age. Hens are 1+ year old pullets, and Cocks are cockerels that are also over a year of age. Your black chick is probably an Australorp, but we'll just have to wait and see.
1st chick: Probably a Light-Brown or Dark-Brown Leghorn, as it has yellow legs. If it were an Easter Egger, it would have greenish legs, and if it were a Sussex, it would have white legs. For now, it looks like a pullet.
2nd chick: Most likely a Black Australorp. However, like Wyandottes7 asked...