Q: Many argue that
vega is just a refined polaris gpu, how would you respond to this ?
A: My
software team wishes this was true

Vega is both a
new GPU architecture and also completely new SOC architecture. It's our first InfinityFabric GPU as well
...
The new geometry pipeline in Vega was designed for
higher throughput per clock cycle, through a combination of better load balancing between the engines and new primitive shaders for faster culling.
As a programmer you shouldn't need to do anything special to take advantage of these improvements, but you're most likely to see the effects when rendering geometrically complex scenes that can really push the capabilities of the hardware.