The primary difference is , you are paying extra for HDR Performance along with some advanced TV features like Variable Refresh Rates ( V-sync for gaming ) & cable management .

An important thing to know ,  despite the current entry levels 4k TV such as NU7100 , XF75, XF70 being advertised HDR TVs , they are not actually considered as HDR compatible . They are merely able to digest the signals , they don't have the hardware specs to display it .
On the other hand , NU8000 is a much brighter TV . It is able to utilize the local dimming to show bright highlights from HDR content so the picture can , to a certain extend "pop" out of screen. The TV also supports a wider color space coverage in both rec 2020 and DCI-P3 , which are what most modern 4k UHD movies are mastered with.

Obviously if you are looking for true HDR experience , neither NU8000 or NU7100 are an ideal choice . The latter doesn't quite nearly has the hardware specs to support it .  The former is not very good at it either . Since edge-lit based local dimming will brighten up the entire portion of the picture when showing bright objects , which effectively reduce the dynamic range of the picture . 
Nevertheless , among the sea of mid range TV models in MY ,  it is the only one which can give you a taste of what HDR is like without forcing you to sell your blood and kidneys.