ΔE 23.7, loose: different enough that you should pick on purpose. Sunset Red is more muted, cooler than C.P. Cadmium Red Dark.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 24). Sunset Red is more muted, cooler than C.P. Cadmium Red Dark.
The same difference applies the other way round: C.P. Cadmium Red Dark is more saturated, warmer.
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 C.P. Cadmium Red Dark on the colour wheel See Sunset Red on the colour wheel
All matches: C.P. Cadmium Red Dark equivalents · Sunset Red equivalents