series 9 watch upgrades?

Were there upgrades to series 9 (41 mm) watches this year? I was told at a Best Buy that the new Series 9 ones removed the oxygen sensors, improved the battery life and changed the material in the face to something more durable. They said all Series 9 Apple watches (41 mm) were not the same, and claimed the ones being sold on Amazon that looked exactly the same and had the exact same description were older Series 9 with lower battery life, so they would not price match. Did Apple make any changes in Series 9 this year? I know they are now discontinued.