I have ds first and dd second and there are definite differences between the 2. Hard to say which are individual differences and which are sex differences.
ds slept really well from very early on, through the night at about 4 weeks, and continued to be a good sleeper, tended to sleep things off, like a cold, immunisations, teething etc. always napped twice a day, sometimes slept on into the night from a nap at 4pm! He has always been more interested in putting things together and taking them apart, he's good at maths and science, he learned to read later than dd and still isn't an avid reader, he's very loving and protective towards me, he's fairly uncomplicated emotionally, either on an even keel (most of the time) or really angry about something and likely to throw things around and shout. He's 13 now, and has been that way all his life. He's started puberty only in the last 6 months, and his voice has just started deepening.
dd was conspicuously language oriented from very early on. she spoke earlier than ds, and used to play games with words just for fun, at 3 she would reverse words sound by sound, which i couldn't do without really thinking hard about it.
she never slept much in the day, seemed to be too interested in what was going on to go to sleep. she still needs less sleep than her older brother. she was a fantastic breast feeder from birth, very effecient and just seemed to know what to do.
she learned to read early and continues to enjoy books and story tapes.
she's quite complicated emotionally, thinks a lot about her own and others' feelings and relationships with school friends.
sorry to blab on, but i do love them both. and ds2 is due any day, so i'll be revising my ideas again.
i honestly think we all have a real mixture of male and female in us. some of us have more female characteristics, emotionally, intellectually, physically etc. and vice versa.