The one ahead of the other looks like it might be a cockerel. How old are they? Age is a key factor in helping determine gender. The breeds they might be are: Rhode Island Reds, New Hampshire Reds, Production Reds, and possibly (but less likely) Amber Stars.
So at their age of about a month and a half old, I'd say the one in front of the other chicken is likely a rooster. The coloring is different and the legs appear to be thick. The combs should start to grow in a couple weeks, and that will also be a good factor for telling if it's really a roo.