One way to define stories

One way to define stories is by their main focus.

Orson Scott Card in his book How to Write Science Fiction and Fantasy gave the MICE mnemonic.

Milieu- the place is the thing
Idea- it’s all about the idea, like an art movie
Character- a person is the main point
Event- some specific event propels the plot forward

Yes, stories may have elements of all of them, but one will be the most important. Introduce them to students by movies. After you’ve explained what they are, ask the students to identify movies where each of those is the focus. That way
1. You won’t be embarrassed when they don’t know any of the movies you referenced.
2. They will correct each other.
3. They can come to a consensus on which best fit.