The answer is very simple, lookbooks are just that, a book to show off the look of a brand. They are usually used by fashion labels to visually show the "look" or idea of their latest collection. Today, they are mostly used by independent brands and fashion bloggers as a way of publicity and promotion.
A lookbook consists of styled images, with models wearing the clothes, and looks just as good as anything you would normally see in a fashion magazine.
Lookbooks are often confused with catalogues but the main difference is that a catalogue has direct product shots, product information, and prices so that people can place direct orders from them.
A lookbook is all about showing a "look". The aim is to create aspirational lifestyle images that customers can relate with.
ZARA LOOKBOOK APRIL 2013
NASTYGAL COLLECTION SPRING 2013 LOOKBOOK
NASTYGAL APRIL 2013 LOOKBOOK