One of literature’s main goals is to entertain. The literature branch devoted to this goal is known as commercial literature or, to give it a better name, entertaining literature. Several genres and subgenres are part of it such as crime fiction, thriller, romance, science fiction, fantasy, horror, etc.
Of course classic literature and literature in general is entertaining but it is not its main goal or is it designed for that purpose. Its main objective is to artistically portrait human condition and research about it in its various times and spaces. Many times entertainment is sacrificed in sake of exploring deep aspects of the human race and portraying a specific view of it and its society, providing a more artistic and intellectual pleasure to its readers.
However it cannot be said that entertaining literature does not inquire about human condition nor artistically depict it. Because it discusses human beings it necessarily does (even when narrating stories about beings from other species, as in fantasy or science fiction, because it anthropomorphizes them or, by contrast, makes us see humans from other angle) if to a lesser extent, giving up that aspect in order to provide entertainment with greater emphasis.
Clearly within this classification some books tend to the ends and others to the middle.
In any case, whenever we write crime fiction, thriller, science fiction, romance, etc. we should constantly remind ourselves that our purpose is to entertain the reader.
Concrete differences between entertaining literature (or commercial literature) and literature in general
The differences I will list in the next post are also differences of scale. This means that a certain difference is not exclusive to entertaining literature but in general it is more important to it though it can also be found in literature in general.