ΔE 10.3, fair: the same colour family, but not a straight swap. Bright Green is a little lighter, more saturated, warmer than Majestic Fortress.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Bright Green is a little lighter, more saturated, warmer than Majestic Fortress.
The same difference applies the other way round: Majestic Fortress is a little darker, more muted, cooler.
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 Majestic Fortress on the colour wheel See Bright Green on the colour wheel
All matches: Majestic Fortress equivalents · Bright Green equivalents