Phalanx Yellow vs C.P. Cadmium Yellow Light

How close are they?

ΔE 22.5, loose: different enough that you should pick on purpose. C.P. Cadmium Yellow Light is noticeably lighter, cooler than Phalanx Yellow.

Can I use C.P. Cadmium Yellow Light instead of Phalanx Yellow?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). C.P. Cadmium Yellow Light is noticeably lighter, cooler than Phalanx Yellow.

Can I use Phalanx Yellow instead of C.P. Cadmium Yellow Light?

The same difference applies the other way round: Phalanx Yellow is noticeably darker, 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.