defination of words
machine: a device with several moving parts which uses power to do a particular type of work:
Eggs are sorted into different sizes by a machine.
If I'm not home when you call, leave a message on the machine (= answering machine).
Don't forget to put the towels in the machine (= washing machine) before you go out.
I got some chocolate from a vending machine.
mill: A common name for various machines which produce a manufactured product, or change the form of a raw material by
the continuous repetition of some simple action; as, a sawmill; a stamping mill, etc.
machine 보다 mill 이 좁은 의미의 기계를 의미하나 여기에서는 차이 없이 사용해도 될 것 같다.