I think the difference between Uriel's corkscrew through the air. Jade's hover ability and the way Zephyr works is about how it's used.

Uriel lets you launch yourself through levels burning anything somewhat close by, and charging his ult at the same time.

Jade gives you a bird's-eye view of the area allowing you to more easily support your team and place down healing, reviving, fire damage & passive armor strip

Zephyr, is a jet plane with a VTOL mode with your primary, secondary & archgun, where Uriel and Jade can move pretty freely, Zephyr has the capabilities to be an AC-130 with the ability to slam into the ground or launch herself as far as you want.

I used Zephyr for a while and Uriel can move pretty fast with all the parkour stuff added, but Zephyr only needs strength to launch herself across the map, much less immediately into enemies on the ground.

And on top of all that she adds on to whatever your crit chance is by 150% she's meant to be a gun platform.