Hi Convael, SoC is same but X1 is a separate IC which means for video DSP.
FYI, I am ex-Sony TV R&D member

hi, i am checking out tvs for new house, am quite new in tv, have been doing research, but would appreciate for your comments incase you have any experience with the model i am considering,
first of all,
1. My budget ~4k plus not more than 4.5
2. I use my tv for movie (mostly action movie) and gaming (ps4)

Currently considering
1. 55” samsung nu8000
2. 65” kd65x7500f

Personally prefer 65 inch tv, but if nu8000 is better, because of budget, i dont mind reducing to 55”. (65” is 6k plus)

It is better , a lot better especially when it comes to HDR capabilities.

The thing of getting a bigger screen is you get a more immersive experience from the larger screen size filling up your vision.

For most people it would be a tough choice , it will have to come down to if you watch enough HDR content to justify the sacrifice of screen sizes.
And since you have a ps4  which has considerable number of HDR games , You are probably better off with NU8000.