What's the different between Collection and Restock button?

On cashless DTU. there are two buttons :  Collection and Restock. Every time you refill your vending machine, need press either one to tell the server machine been restocked.

The difference between these two buttons is:

When you press the Restock button, it will put current level of all coils back to Par level.

Collection button will do the same thing, plus, create a collection report which you can see under Collection->History Record menu.