I'm not sure if there's a way to check (afterwards) what has been used to repair the laptop.
There isn't but refurbished is close to brand new but might have not come in the original packaging (refering to parts of the machine).
Hardly a commercial decision from their perspective; £395 on a logic board, £300 on a screen. Surely if they gave me a new machine, and sold mine with a refurb they would have saved costs. I suppose that is why they work in retail....
There are some lucky people,who also write on this forum about being given a brand new machine but in most cases apple offers to repair everything instead of giving you a new one... experienced it myself...