A Linear narrative structure is one that is told in chronological order, an example of a linear story is Toy Story (1995), Disney Pixar, which is told simply from start to finish.
A Non-Linear structure is one that is told out of chronological order, a good example of a non-linear story is Memento (2000), Christopher Nolan, which is told backward.
Many stories have parts of both, either they are linear, with ‘flashbacks’ which are none linear (as they do not happen at the time of the event with in the story) or they can be non-linear, but are often told in a linear manner (small plots running from start to finish (linear) but shown in a non-linear fashion).
This is where the narrator of the story is speak in the here and now.
This is when the author is speaking retrospectively.
The discourse of the narrative is the theme, which can be as vague as tragedy, romance, comedy or more specific in terms of hindsight etc.
Each of my small stories will follow these set of rules.