ΔE 10.4, fair: the same colour family, but not a straight swap. IJN Medium Grey is a little darker than Bright Warm Grey.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). IJN Medium Grey is a little darker than Bright Warm Grey.
The same difference applies the other way round: Bright Warm 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 Bright Warm Grey on the colour wheel See IJN Medium Grey on the colour wheel
All matches: Bright Warm Grey equivalents · IJN Medium Grey equivalents