Great question!

So, the settings list and the definitions list can overlap, but they're not exactly the same.

Setting is physical and cultural surroundings where your story (and its individual scenes) take place. It could be a kitchen, a bowling alley, the state of Maryland, the country of Russia, Mars. In your settings list, you're listing where your story takes place and where your scenes take place.

If your story takes place in a bowling alley, you might want to include some definitions like: what is a strike, a spare, a split? How does scoring work? Those may seem insignificant, which is fine, you don't have to list those things on your definitions list. BUT - if your story follows an underdog bowling champion who makes it to nationals, you might want to include a brief list of the relevant tournament rules, or, even better, a link to the Professional Bowling Association's League Bowler Certification Rules.   That would be something you might like to reference routinely as you're writing the story.

Think of the definitions list like the glossary at the back of your book. It's going to include words or phrases that your reader may or may not already know. But it's really for you, so you can have that glossary handy while you're novelling.

Actually, it might help to have a little insight into your story. Do you mind sharing it? You could also IM or email it. We could brainstorm things you might want to define in advance.

The Cheerleading Fairies caught you
INITIATING DISCUSSION!

You get a prize:

Cheers,
Michelle