5120 × 2880 vs 6016 × 3384
5K against 6K, side by side.
6016×3384 renders 5,612,544 more pixels than 5120×2880 — 38% more. Both are 16:9 displays, so content fits identically — the difference is pure pixel density. At 6K's pixel count you'll typically run OS display scaling above 100% for readable text.