ΔE 11.5, fair: the same colour family, but not a straight swap. Ultimate Cup of Coffee is a little darker than Regiment Grey.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Ultimate Cup of Coffee is a little darker than Regiment Grey.
The same difference applies the other way round: Regiment Grey is a little lighter.
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 Ultimate Cup of Coffee on the colour wheel
All matches: Regiment Grey equivalents · Ultimate Cup of Coffee equivalents