Nuance
Etymology
From French nuance, “shade of color,” from nuer, “to shade,” from nue, “cloud” (ultimately Latin nubes, “cloud”). The image is the graded shading of clouds, which passed into “subtle variation of color” and then into any subtle distinction of meaning or tone.
noun · /NOO-ahns/
A subtle distinction or shade of meaning, feeling, or expression.
What it names
The small, easily-missed differences that change the whole sense of something — the fine gradations that blunt words like “difference” flatten out.
Example
A good translator preserves the nuance between “house” and “home,” not just the dictionary meaning.
Related idea
Subtlety is the quality of being hard to notice; a nuance is a specific small distinction. You can miss a nuance because of its subtlety.