The end point of successful pollination in angiosperms resulting in part in generation of endosperm.
Double fertilization literally consists of two fertilizations. The end point of one of those fertilizations is the zygote, i.e., the first cell of the sporophyte generation. The other fertizliation is of a quasi-diploid cell that results in formation of the endoderm.
Both nuclei that are involved in this double fertilization come from the same pollen grain.