The Minichamps model is at 1:43 scale and is typical of their usual high-quality, where as the Welly ones are 1:87 and 1:24. Stuart, the Welly model in your is the 1:24 model, which I have seen for about £7 elsewhere, rather than the 99p one you can get in Wilko's.
Both the Welly models make ideal childrens toys but the detailing is crude, although perfectly acceptable at that price. The Minichamps model is more, but as a display model is, in my humble opinion as an anorak collector, worth every single penny.
I look-out for Minichamps, Auto-Art and Kyosho models as the high-quality and acceptable-price option or Sun Star as the decent-quality and low-price option. Norev models vary, I have a simply stunning Citroen GS 1:43 model but some of their stuff is shocking. Unless you have seen the model and are satisfied with the quality and price then buying off the net is a bit of a gamble.
Oh, and before Wooly Pipes-in, that Skoda 120L model is worth every penny and a fine addition to the collection
EDIT: Oh, and the models in the link look well-priced but check-out the postage prices!