When I sit down to write a story, play, or novel, I begin with CHARACTERS. I put my CHARACTER(S) in a setting and watch what happens. For example, I notice that both Keith and Robert met and became friends at school and are now businessmen but no longer friends. This is because Robert's business is successful but Keith's isn't. Keith is resentful and jealous of Robert's success. There are three possible THEMES here: friendship, business success, and jealousy.
Together, the CHARACTERS and THEMES give me a list of EVENTS: for example,
1. Keith spreads rumours that Robert uses underhand business methods
2. Robert hears what Keith is doing and refuses to speak to him, ending their friendship
3. Keith and Robert both played in their high school football team
4. At school Keith was keen on Wendy Pirbright but she dated Robert instead
5. When Keith's business is on the point of being declared bankrupt Robert offers to help Keith out
6. At Robert's wedding to Wendy, Keith meets Wendy's attractive younger sister
and so on. These are EVENTS, and therefore a writing plan, but they aren't yet a story because they have to be shaped--put into a sequence; this is what we call PLOT. For instance, you might decide that the story should begin with Keith and Robert still friends at high school, or you might decide to begin with Keith losing Wendy to Robert or with Keith spreading rumours or... Whatever you choose, it means ordering the EVENTS. The order is the PLOT and when the EVENTS have been written in their desired order you have a story.