Tom's have beards, but be careful there, I've seen many bearded hens in my day as well. Toms have red, white and blue heads and strut and gobble, hens don't. Well, I've seen hens kind of strut, but it's a dominance move, not a display move. Toms are a lot darker black than hens, hens are more of a brown....Toms are typically larger as well.

You can tell a jake from an adult tom when they strut. Thejake will have 2 or 3 tail feathers in the center of the fan taller than the rest. Adult tom's will have even fans.