I've just been directed here from the other thread about gender differences.
I have 5 children- 2 girls and 3 boys. The boys and one of the girls are adults, so I'm not just going by what they were like as toddlers.
DD1 walked early, talked early. Very active, loved to jump and run about. Refused to dress as a girl. Not interested in dolls, or cars. Would sit and listen to stories. Loved music and learned piano. Now loves to read, is very active- into martial arts etc, but now dresses as a girl
DS1 very quiet. Happy to sit in pushchair and watch the world go by. Walked and talked early. Liked Lego and things with wheels. Loved to draw. Good at maths but anti-social. Never reads fiction.
DS2 has ADHD. Crawled at 4 months, walked early, talked early. Hyperactive. Into computer games. Loves to read fiction.
DS3 did everything late. Didn't sit up until 9 months. Walked later and talked later than the others. Very cuddly and into soft toys and pretend games. Did dancing for most of his childhood but otherwise average level of activity, unlike his brother and sister. Will not read for pleasure. Taught himself to play various instruments.
DD2 is still little. She was much much later walking and talking than all her siblings. She climbs, she jumps. She rolls in mud. She is never still and never clean. Needs little sleep. Won't sit quietly for a story. Loves dolls. Loves to draw and paint. Loves to swim.
They are five totally different personalities, not "boys" or "girls". A huge amount of gender differences are learned at preschool when they come together with other children who have been brought up to believe that "girls do this" or "boys do that".