Mac Mini M4 New v’s Refurbished (UK)

I'm in the process of looking to buy a Mac Mini base version and have two options.

Amazon has a brand new one for £528.98 but I just had a look at Apple Refurbished and they are going for £509.

Apart from the obvious are there any other major things to look out for when buying a refurbished as opposed to brand new.

Also, from experience can we expect to see any Black Friday deals in the UK for a Mac Mini M4.