Gear S3 Frontier vs Galaxy Watch3 - Technically it's a marginally thinner but smaller housing, narrower bezels, and weighs significantly less. It feels thinner than it looks, maybe due to the back
Hands-On: The Samsung Gear S3 Smartwatch Classic And Frontier (Designed By The Guy Who Brought You The Titanic DNA Watch From Romain Jerome) - Hodinkee
Samsung Gear S3 Specs (Frontier vs Classic) – Phandroid
Samsung Gear S3 Frontier review - Almost perfect stylish and cool Smart Watch | TechNave
Samsung Galaxy Watch 46mm Vs Gear S3 Classic What's The Difference? - YouTube