The only thing that really separates men/vs woman in the work place is maternity leave.
Not so. Physical prowess, physical beauty and sexual harassment also separate the two. Women are also members of a protected class - Age, Color, Disability status, Familial status, Genetic information, National origin, Race, Religion, Sex, Veteran status.
Equal pay for equal work can be a little hard to prove at times. When Main Lady was working for the State of Ohio, she discovered a discrepancy in the pay rates between men and women who were doing the same job. When management was a good deal less than enthusiastic about fixing the situation, Main Lady organized a labor union, participated in union negotiations and got the workers salaries adjusted and back pay given to those that had been cheated out of it for years. Then, since the union was successful, AFSCME horned in, rigged an election and took the whole thing over. And that was that.
The real problem is that if you think you're being discriminated against, you probably are. Proving it is something else, and even if you win a lawsuit it may be a somewhat Pyrrhic victory.