Step-by-step explanation:
I believe the first one is saying that your pay should be based on your work performance. If you are doing a good job, you should be given a good paycheck, "equal pay for equal work." if you are performing poorly than you be given a small amount, all based on work performance. For example, sales. How much you are able to sale will determine how much you would get paid.
The second one
1. comparable work as in how consistent you are, for example you do good one day and bad the other day.
^ I would explain further but I have to go to bed, hope you understand what I mean and hope this helps!