Female moose do not have or grow any antlers.
Only the male moose grows and has antlers.
If you see a moose that has antlers then the moose is a male moose and if you see a moose that has no antlers then the moose is a female moose.
The same is true with Elk as the male Elk only has antlers and the female Elk does not have antlers.
If you see an Elk with antlers then the Elk is a male Elk and if you see an Elk without the antlers then it's a female Elk.
The antlers is an easy way to know whether a moose or an elk is a female or male.