Answer: Context
I get how Nikolai is working at home and will be getting paid $20 but despite the $25 being at a factory and is repetitive, here is a little word from experience. The $25 is a start-off which is pretty good and it won't always be at a factory. If Nikolai is working hard and repetitive, he will be promoted to the fact where he will be paid more and work at home time-to-time. The $20 one, however, is a work-at-home type and since there is children, the house will have to be quiet during calls and what-not.