Differences between rx 580 4gb vs rx 580 8gb.?

So I have 4gb version and want to upgrade. but they told me 8gb was only for 4k gaming, and there would be no real difference in performance. I have 1080p monitor and i'm not planning to play in 4k. So will 8gb give me more fps and better texture quality in 1080p or no?

AVDADDY: https