The Inspire 2 offers a more refined design with softer, curvier edges and an inductive button over a physical button, as well as double the battery life.
The Fitbit Versa 3 offers built-in GPS, a built-in speaker and Google Assistant on top of Amazon Alexa. There is also fast charging.
The Fitbit Sense offers more features than the Versa like an EDA sensor, skin temperature sensor and the ability to take an ECG.
The Fitbit Iconic feature a more sportswatch design but still has made of the same cool tech as the Versa and Sense models.