Pay Gap?

less skill, less qualifications, less physical strain, less mental strain, less risk, fewer and more flexible hours, maternal leave....

Shall I go on?

But what about when they are working the exact same jobs and there is a pay gap?

Since that's illegal and has been since the mid 1970s. That can only really happen if she's doing less hours or overtime for that exact same job, or, if she's less experienced than the man is, or he's been at the company longer.