1920 × 1200 vs 2560 × 1600
WUXGA against WQXGA, side by side.
2560×1600 renders 1,792,000 more pixels than 1920×1200 — 78% more. Both are 16:10 displays, so content fits identically — the difference is pure pixel density.
The two 16:10 tiers of the laptop renaissance. 1920×1200 is comfortable at 14 inches and cheap to drive; 2560×1600 adds real sharpness that's easy to see in text, at some cost in battery and price. On external monitors the split is by size: 24 inches suits the former, 30 the latter.