The 965 is best viewed as the 955 with an AMOLED, in that sense.

The Fenix is just a Garmin Epix with an AMOLED display.

This means that you receive all of the same features that make it a powerful run-tracking

 tool as well as a versatile sports tracking tool.

The optical sensors are the same, and one of them tracks blood oxygen data.

However, using it continuously uses more battery than continuously monitoring heart rate does. 

 You will receive the same support for your satellite system,