Both boys. Those are Barred Plymouth Rocks, Barred Rock or BR for short. You can tell the sex of any barred bird at a very young age, the females will be very 'dark' (like the pullet next to the big guy on the roost) while the males get very 'light' early on. Some can sex them at day-old because of the size and shape of their head spots as well as coloring on the legs.
ETA: After looking at the pics again, I believe they are Cuckoo Marans...the barred thing still stands and they are still boys though
Yeah, I edited my post about 20 minutes before you posted, I always forget to look at the legs on them! I think they are definitely Cuckoo Marans because of the white legs, but the barred thing for sexing still holds for them.