ΔE 14.6, fair: the same colour family, but not a straight swap. Flat Flesh is noticeably darker, more saturated than Sunburned Skin.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Flat Flesh is noticeably darker, more saturated than Sunburned Skin.
The same difference applies the other way round: Sunburned Skin is noticeably lighter, more muted.
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 Sunburned Skin on the colour wheel See Flat Flesh on the colour wheel
All matches: Sunburned Skin equivalents · Flat Flesh equivalents