Males have lower and deeper voices than most females do because males have longer vocal cords than females do.
Adult males have longer vocal cords of up to 1 inch (2.54 centimeters) in length while females have shorter vocal cords which causes the higher pitched less deep voice.
The shorter vocal cords is also the reason for higher pitched voices in male and female children.
When you're a child that has not gone through puberty yet your vocal cords are shorter and you have a higher pitched voice which then eventually changes as you get going through puberty.
As you go through puberty your voice begins to crack and it can be hard to talk properly.
But as you go through puberty your vocal cords get longer and you get a deeper voice.
The hormone Testosterone is what causes the vocal cords to increase in length and your voice changes to the deeper voice that you have as a teenager and adult.