From a brief Google search these are your movement variations. Omega 8500 is a gents automatic with date Omega 8501 is a 8500 with 18k rose winding rotor and balance bridge Omega 8601 is an annual calendar with date and month at 3:00 Omega 8611 is a 8601 with 18k rose winding rotor and balance bridge Omega 9300 is a chronograph Omega 9301 is a 9300with 18k rose winding rotor and balance bridge Omega 8520 is a ladies automatic with date Omega 8521 is 8520 with 18k rose winding rotor and balance bridge Omega 8421 is ladies automatic with No date I believe that the 8500 proper is mainly found on the seamster non chrono watches with the exception of the smp300cx which carry the 2500. Also as you see the different models come out refer to the list for complication changes in model #. also the master coaxial movements are 8400 for the smp300 and 8500 for the AT (I think the variation is only on the date complication but am not 100% sure) the older non master coaxial are also 8500's I hope I got it right rot you.
Yea Hour Vision, DeVille prestige, Tresor, Ladymatic are all available with 8500 or 8500 derived movements now, though there's some others in there too
Well Snick777 I think best you can do is get the Omega App or go to the website under "collection" and get your notepad and pencil ready...better you than me