Cisness is the biologizing ideology that these social roles of sexual difference adhere to assigned sex based on the appearance of genitals at or (via prenatal imaging technologies) before birth. In other words, cisness is the idea that those identified as girls at birth are naturally inducted into the social expectation that sexual difference sets for the feminine and likewise for boys with the masculine. So, as is clear from these definitions, both sexual difference and cisness are ideological constructs, but of different types.
