Terminologies and definitions

Does a list of terminologies and definitions exist anywhere? I haven't been able to locate one.

After watching videos numerous times, I'm still not confident in my understanding of how best to use what feature. While some terms are clearer than others, it would be valuable to understand the pros and cons, as well as, the intended use of each. Terms like, but not limited to; items, parts, folders, gray folders, lists, product, product lists, etc.