According to Wollstonecraft, those distinctions between men and women that she deems as unnatural are those that have been constructed by patriarchal society. That is to say, they arise out of conventions and traditions; they are not in any way related to natural distinctions, the biological differences between men and women.

As an example of unnatural distinctions, Wollstonecraft cites the confinement of women to the sphere of the home. In Wollstonecraft's day, women were expected to be nothing more than wives and mothers. The idea of women pursuing a career outside of the home—except perhaps as maids or governesses—was considered unacceptable. Wollstonecraft thinks this is a criminal waste of women's talent. It is also patently unfair, as it deprives women of the chance to show their (natural) virtues.

That's not to say that Wollstonecraft envisages women as not having the most important role to play in raising children; for her, this is an expression of natural differences between the sexes. But in a crucial twist she adds that such natural differences are obscured by unnatural differences that keep women in a state of subjection to their menfolk. Wollstonecraft argues that women would be able to show more affection toward their husbands if they enjoyed more independence. This is because they would've chosen whom to marry instead of being deprived of such a choice through the imposition of social roles designed to keep men in a position of power and control.

Even today, there are still many unnatural distinctions that prevent true equality between the sexes. To a large extent, career choices are still determined by social convention, with certain professions—such as nursing or care work—largely the preserve of women, and others—such as computing and construction—the preserve of men.

When Wollstonecraft talks of unnatural distinctions between men and women, she's referring to those artificial differences imposed by custom and tradition. Natural distinctions, on the other hand, are those arising out of the biological differences between the sexes. One such example, according to Wollstonecraft, is the "natural affection" that makes women good wives and mothers but which they are prevented from displaying by a want of virtue arising from a lack of independence.

Examples of unnatural distinctions could include the respective roles that men and women play in society. In Wollstonecraft's day, men were expected to be the bread-winner while women stayed at home to look after the children. Wollstonecraft believes such an unnatural distinction to be grossly unfair. She argues that if women were able to pursue careers like men, then many of them might be saved from what she calls "common and legal prostitution."

By "legal prostitution" Wollstonecraft is referring to the situation in which many women found themselves in her day: getting married to men they didn't love simply in order to have a stable home life. Such a distinction is unnatural because it isn't based on the innate characteristics and talents that women have and which they could use to achieve true independence, if only they were allowed to. Distinctions such as these are imposed on women by a patriarchal society which seeks to maintain men in a position of power and authority.

Though things have changed an awful lot since Wollstonecraft's day, there's still a long way to go towards achieving genuine equality between the sexes. The gap in pay between men and women continues to be a persistent problem, as does the common prejudice that certain careers—such as science and engineering—are somehow not suitable for women. Wollstonecraft would certainly have described these as examples of unnatural distinctions and would've challenged them with the eloquence, vigor, and determination for which she was famous.