Here's why:
* No external differences: Unlike some animals, fawns don't have any obvious physical differences in their external genitalia that would allow you to distinguish their sex.
* Developing antlers: Male deer (bucks) will eventually grow antlers, but these don't start developing until they are older.
* Best way to determine sex: The only way to determine the sex of a fawn with certainty is through a physical examination by a wildlife professional.
So, unless you are a trained wildlife expert, it's impossible to tell the difference between a male and female fawn just by looking at it.