•Megaspores are produced by meiosis in megaspore mother cell. Megaspore then develops into female gametophyte or embryo sac. •Megagametophyte or the female gametophyte is the embryo sac that develops from the megaspore through megagametogenesis. •Megasporangium is a structure which along with its protective coverings forms the ovule. •Female gamete is the egg cell which upon fusion with male gamete forms a diploid zygote. Hence, embryo sac represents megagametophyte.