Crimson vs Sunset Red

How close are they?

ΔE 22.8, loose: different enough that you should pick on purpose. Sunset Red is a little darker, much more muted, cooler than Crimson.

Can I use Sunset Red instead of Crimson?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Sunset Red is a little darker, much more muted, cooler than Crimson.

Can I use Crimson instead of Sunset Red?

The same difference applies the other way round: Crimson is a little lighter, much 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.