No, it isn’t.
UltraHD and 4K are the same thing, while HDR is something fundamentally different.
Look.
4K TV has four times more pixels than FullHD TVs (1080p).
HDR doesn’t care how many pixels it has to work it – it just takes advantage of their capabilities.
So it’s not the same. The UHD refers to resolution, while HDR refers to contrast and colors.