They don't really.
Intonation maybe. They could sound the same if they weren't exposed to feminine and masculine ideas of voice.
Girls has smaller vocal cords, which vibrate at a higher frequency.
Boys vocal chords grow 3mm more per year than girls, so they are slightely longer, resulting ind a slightly different pitch. puberty causes mens chord to get thicker & longer causing their voices to drop. Googled it.
It's coz of puberty dude! Boys have different vocal cords to girls, so they're voice deepens at around the age of 14-15 etc... Even my voice hasn't deepened yet.
Justin Bieber still sounds like a girl.
Males are still geared towards testosterone even when they're little boys they just don't have that massive jolt of it until puberty.
Isnt it so annoying when your voice breaks and you go from high to low to nothing coming out in a single sentence. fond memories lol