They are not identical, however the women have double x's (XX) and the males have an X and a Y (XY) the y is what determines the sex of male. In other words if there is a Y, then you are certain it is a male.
No. The Y chromosome is much smaller than the X chromosome. There are only about 70 active genes on the Y chromosome and many more deleteriously mutated one. The X chromosome contains many more...
No. The human X chromosome contains over 1000 genes, many of which are essential for life. The Y chromosome in comparison has only about 120 genes. A zygote with Y0 or YY (one or two Y chromosomes)...