The types of tasks performed in the Library module generally fall under file management, such as separating the keepers from the clunkers, applying keywords, organizing into collections, renaming, applying metadata, etc., and each of these views are designed to help make those tasks a little easier.
The four Library module views—Grid, Loupe, Compare and Survey—are accessible from the Library module Toolbar.
Read The Many Views of the Library Module over at peachpit.com.