Parthenogenesis, a reproductive strategy that involves the development of a female (rarely a male) gamete (sex cell) without fertilization. Parthenogenetic species may be obligate (that is, incapable of sexual reproduction) or facultative (that is, capable of switching between parthenogenesis and sexual reproduction depending upon environmental conditions). An egg produced parthenogenetically may be either haploid (i.e., with one set of dissimilar chromosomes) or diploid (i.e., with a paired set of chromosomes). The production of female offspring by parthenogenesis is referred to as thelytoky
Sexual dimorphism refers to the condition where the two sexes of the same species show different characteristics apart from the differences in their sex organs.
As both sexes consist of different chromosome pattern ( for e.g. XX AND XY in human beings), they differ genotypically.
Those observable characters which are visible to us and helps us in knowing the sex of any animal/plant without knowing their chromosome pattern are essentially what phenotypic difference is about.