ΔE 10.1, fair: the same colour family, but not a straight swap. Cadmium Red Medium Hue is a little darker, more saturated than Legendary Red.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Cadmium Red Medium Hue is a little darker, more saturated than Legendary Red.
The same difference applies the other way round: Legendary Red is a little lighter, more muted.
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 Legendary Red on the colour wheel See Cadmium Red Medium Hue on the colour wheel
All matches: Legendary Red equivalents · Cadmium Red Medium Hue equivalents