difference between pollen sac and embryo sac

POLLEN SAC : A chamber in which *pollen grains (microspores) are formed in the angiosperms and gymnosperms. It is homologous with the *microsporangia of the pteridophytes. In angiosperms there are usually four pollen sacs in an anther, arranged in two lobes, either side of the connective tissue. In the conifers there may be numerous pollen sacs formed on microphylls in the axils of the male strobilus.  EMBRYO SAC :n most flowering plants, only one megaspore is functional while the other three degenerate. The single functional megaspore develops into the female gametophyte or embryo sac. This kind of development is called monosporic development. The nucleus of the functional megaspore divides mitotically to form 2 nuclei, which move towards the opposite ends, forming a 2­nucleate embryo sac. Two more mitotic divisions ensue, leading to the formation of 4­ nucleate and 8­nucleate embryo sacs. After the 8­nucleate stage, the cell walls are laid down and the typical female gametophyte (embryo sac) gets organised. Six of the 8­nuclei get surrounded by the cell wall and the remaining two, called polar nuclei, are situated below the egg apparatus in the large central cell. Three of the six cells are placed at the micropylar end and constitute the egg apparatus (2 synergids + 1 egg cell). The synergids have special thickenings at the micropylar end. These are together called the filiform apparatus. It helps in leading the pollen tubes into the synergids. Three cells are at the chalazal end, and are called antipodal cells. A typical angiosperm female gametophyte is 7­celled and 8 ­nucleated at maturity.

female gametophyte or megagametophyte also called embryo sac
pollen sac is microsporangia which will produce pollen grains