A man's legs tend to be a little bulkier than a woman's legs. A woman's legs tend to be a little curvier at the hip, more narrow/delicate at the ankle. In SOME cases a woman's legs resemble those of a young boy (or vice versa) because they share a thin, lanky build.
Yes due to the bone structure. Also the thickness and length of the hair. Girls generally have thinner/finner hair than guys and it's not as long. Well this is me comparing myself to my brother when I haven't shaved or waxed in a long time aka winter (6 months). Lol.