The Apple Watch Series 9 design is identical to the Watch Series 8 to the millimetre, but the brighter display and the new SiP makes all the difference.
Apple Watch Series 9 vs. Series 8: Which model should you buy?
Apple Watch Difference Between Series 8 and 9: Key Upgrades Analyzed - GadgetMates
Apple Watch Series 9 vs Series 8 - PhoneArena
Apple Watch Series 8 Vs. Fitbit Sense 2: Which Smartwatch Is Best?
Go Big or Stick With the Basics? Apple Watch SE vs. Series 8 vs. Ultra
Apple Watch Series 8 review: The best gets a little better
Apple Watch Series 9 In-Depth Review: A Sports Focus
Buy Apple Watch Series 9 GPS, 45mm Midnight Aluminum Case with Midnight Sport Band - S/M - Apple
Apple Watch Series 9 vs. Series 8: Should you upgrade?
Apple Watch 9 Specs: How It Compares to the Series 8, Series 7 and Series 6 - CNET
Apple Watch Ultra 2 vs. Watch Ultra: Specs, Features, Pricing Compared