Bright Red vs Martian Orange

How close are they?

ΔE 10.7, fair: the same colour family, but not a straight swap. Martian Orange is noticeably darker than Bright Red.

Can I use Martian Orange instead of Bright Red?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Martian Orange is noticeably darker than Bright Red.

Can I use Bright Red instead of Martian Orange?

The same difference applies the other way round: Bright Red is noticeably 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.