ok, let me:

category 1 words are those that are in common use, and most people would know without discussion.

category 2 words are those that some people will know, especially those with a higher education and/or an interest in language. they are likely more precise terms for relatively common experiences.

category 3 words tend to be what might be called "35-cent words" (used to be a nickel but inflation, you know). they could be interest based; jargon, technical terms, or just much more esoteric than common usage.

some people would consider the use of category three words to be elitist, and sometimes, of course, they are used thusly, but it might just indicate that the user loves language.

formerly known as etaoin...