Having scoured the two web pages, other than the price difference, I don't see any difference in specification. Apple's own website doesn't list the EAN numbers used by the Argos retailer.
So as to avoid disappointment on Christmas Day, be aware that Apple now does not include a Power Adapter with iPad. The box will contain the iPad and a USB-C to USB-C charging cable. For the UK (and EU) markets, the recommended Apple 20W USB-C Power Adapter is an additional purchase.
Be aware that Apple will be running its Black Friday event from 29th November to 2nd December - where you will see a small discount by way of an Apple Gift Card to redeem against a future purchase. This might be applied to purchase of a USB-C Power Adapter for the iPad - which, presumably, you will need to consider if purchasing an iPad.