The difference between a poet or literary author on the one hand and a nonliterary author on the other is that the first writes out of an inner necessity, trying to impersonalize all that he or she writes. The nonliterary author generally writes because they have to comment on, or react to, something in the outside world. The literary author internalizes and then generalizes; for them the reaction to an episode is a reaction to the universe. Nonliterary authors give vent to thoughts that pass their minds; whereas literary authors deal with ideas more than thoughts.
The distinction between ideas and thoughts is a subtle one. Ideas are thoughts formulated into general principles. Other writers also formulate their thoughts but move toward facts, dogmas or philosophies rather than ideas.
Both kinds of authors, the literary and the nonliterary, have their politics. But the literary eye goes a little beyond the here and now whereas the nonliterary has more immediate problems to attend to.