ΔE 7.2, close: similar, with a visible difference side by side. Decal Softener is more muted than Insignia White FS 17875.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Decal Softener is more muted than Insignia White FS 17875.
The same difference applies the other way round: Insignia White FS 17875 is more saturated.
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 Insignia White FS 17875 on the colour wheel See Decal Softener on the colour wheel
All matches: Insignia White FS 17875 equivalents · Decal Softener equivalents