I know I'll pay for derailing this, but thanks a lot. My biggest confusion was that these overlap so much, and that they contain the full content.

Again, apologies. I just got curious and was hoping the author might share why this is the case.

Even after following your links I'm confused, but - I got the gentle nudge and understand that this isn't the right place to continue this.

og:description - "A one to two sentence description of your object."

twitter:description - "Description text will be truncated at the word to 200 characters."

itemprop="description" - "A short description of the item."