This catalogue and argos parted company some years ago now, they have now joined forces with littlewoods and are run by the same company.

Most of the items in the additions catalogue are the same as littlewoods but they are cheaper if you intend to pay for them earlier.

Additions catalogue although it merged with littlewoods still kept its own payment scheem.

With additions you get 3 months interest free credit on anything you buy from them so as long as you pay for it in 12 weeks you dont pay any extra.
After that they start charging you interest at 29.9%apr.

Additions catalogue is ideal if you pay before the interest free period runs out as there items are a couple of pounds cheaper than littlewoods but you dont earn commision with additions like you do with littlewoods.

Additions take about 7 days to deliver your order, i dont know why seen as it is coming from the same warehouse and with the same driver as littlewoods items do but it takes 4 days longer and additions also charge you a delivery charge which is free with litlewoods.