One view says that fairness is about aggregate outcomes. We can observe that certain groups appear to be suffering from poor outcomes, and we regard this as unfair to members of those groups. We also recognise the historical factors involved in producing those outcomes. So, we might say "Women are under-represented in the software industry. This is because there are fewer women with relevant skills. But this is because of a legacy of centuries of sexist discrimination against women, and the only way to correct this is to perform some balancing discrimination in favour of women now". This view has no problem in recognising that women can be, on average, "inferior" (less experienced, say) programmers, but says that if they are inferior then it is because of historical factors and not any innate characteristic of women.

The other view says that fairness is about individual acts. It's unfair to take certain aspects of a person's identity (e.g. gender) into account when evaluating a person, so we don't do that. It's unfair to act in a way that makes people of certain identities uncomfortable or disadvantages them in group situations, so we don't do that. Since advantage is relative, it's also wrong to act in a way that benefits only people of a certain identity. They think that disadvantaging someone because of their identity is unfair to that person, and even giving a person a positive advantage is unfair to them because it demeans their real achievements.

Followers of the two ethical frameworks have a lot of trouble understanding each other. The second group thinks fairness is about acting fairly towards individuals, and thinks that it would be wrong to treat a woman differently from a man, since that is, after all, the sine qua non of sexism. But this also rules out giving the women a positive advantage. This directly conflicts with the notion of fairness held by the first group. They will, bizarrely, both describe the other group as being 'sexist' - group one for believing that it's legitimate to treat women differently from men (but only if it is done to correct a historical imbalance), and group two for arguing that it's wrong to consider gender when dealing with someone, because this ignores historical and systemic factors.

I lean towards the individualist position myself, but it's not wrong to worry about the systemic factors and the aggregate outcomes. I also suspect that whilst the philosophical debate is very entertaining, it's also not very relevant to day-to-day life, which would be vastly improved by putting the philosophy to one side and just being a bit nicer to each other.