ΔE 6.5, close: similar, with a visible difference side by side. Incubus Purple is a little lighter, more muted than Regiment Grey.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Incubus Purple is a little lighter, more muted than Regiment Grey.
The same difference applies the other way round: Regiment Grey is a little darker, 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 Regiment Grey on the colour wheel See Incubus Purple on the colour wheel
All matches: Regiment Grey equivalents · Incubus Purple equivalents