What's The Point of 51mm Option When The Screen Size Is The Same Even With Venu 3 ?

I really want to be convinced with a logical explanation about this;

Epix Pro (Gen 2) 51 MM: PHYSICAL SIZE: 51 mm - DISPLAY SIZE: 1.4” (35.56 mm) diameter

https://ibb.co/GWg1D04

Venu 3 45 MM: PHYSICAL SIZE: 45 mm - DISPLAY SIZE: 1.4" (35.40 mm) diameter

So, what's the point of making 51mm option if i could get the same usable screen size with Venu 3 ? Garmin shrinked the bezel but didn't fill the gaps with the screen itself, just closed the gap with unoperational/unusable black lines again.