Synonyms help us connect unknown words with known words. For example, one may not know the meaning of the word "nefarious" when used in this context: "The offense was more nefarious than previously thought." If we replace "nefarious" with "evil" or "wretched" the meaning is more comprehensible to those who don't know the meaning of "nefarious": The offense was more evil (wretched) than previously thought."
I hope this helps, I used nefarious as a somewhat uncommon term to better illustrate my point, and to explain why we use synonyms to learn new words. Simply put, synonyms bridge us to the unknown using the known as solid ground build from.
Roses are red
Sky is blue
people love
so I do
hop this is what you ask
Plot! Plot can change a movie and define its genre. For example, if the plot is in space and is about the future, then this would most likely be called a Sci-Fi movie. Hope this helps!