ΔE 9.4, close: similar, with a visible difference side by side. Heavy Warm White is a little lighter, more muted, cooler than Quartz Skin.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Heavy Warm White is a little lighter, more muted, cooler than Quartz Skin.
The same difference applies the other way round: Quartz Skin is a little darker, more saturated, warmer.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Quartz Skin on the colour wheel See Heavy Warm White on the colour wheel
All matches: Quartz Skin equivalents · Heavy Warm White equivalents