The largest store would be categorised as a department store. This means that it has various departments and brands under one roof. It inlcudes well known stores like Selfridges, Debenhams, John Lewis and Harrods.
Westfield is a very good example of a multiple store. It is an extreeamly well know shopping mall that has a whole range of shops under one roof.
Another retailer is a Multiple Store. This is a store that has chain of store that includes 10 or more branches and that it reaches out and attracts a wide market, this would be a store like Westfields.
Selfridges is an extreamly large store that caters to every need within their store. They offer clothes and accessory shopping along with personal shopping available to guide you. As well as a beauty department for you to shop in. Also they have a large food section where there is little resturants, food shopping and beverages.
There are also retailers known as an "Internet Shop." These are retailers that trade only online, this can be both national or international. It can also be associated with a physical shop. As an example it can be online retailers like ASOS, BooHoo and Pretty Litte Things.
ASOS is an online website only that sells their own ASOS and ASOS White collection along with selling hundreds of other brands, some brands can be found instore and some other brands are only online brands that are sold on ASOS.
The online retailer is based in the UK but ship internationally.
They also have ASOS Marketplace which is also online only.