I've been hunting into Oknas and i have found out plenty of details. The Starmark has a thicker frame And that i don't love that a lot. The 500 and 800 are certainly similar as far as the body goes. The 800 has lesser lifting rails (I think they look https://plastov-okn08742.blgwiki.com/2133253/5_simple_statements_about_okná_hneď_explained