The maternity leave is all a part of the deal for women in the workplace. It generally covers the time immediately after pregnancy when the woman is first learning how to be a mother. Parental leave is usually allowed on compassionate grounds. Maternal leave only applies to women, while the parental leave is given to men as well.
It generally encompasses paternity as well as adoptive paternity. It is also granted to mothers or even the grandparents in some countries. The full amount of maternity leave varies around the world. It all depends on the country and its local laws. It is generally paid leave, and any time past the maternity leave will be unpaid.