Titan Mars Pale vs Ice Yellow

How close are they?

ΔE 18.8, loose: different enough that you should pick on purpose. Ice Yellow is a little lighter, more saturated, cooler than Titan Mars Pale.

Can I use Ice Yellow instead of Titan Mars Pale?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Ice Yellow is a little lighter, more saturated, cooler than Titan Mars Pale.

Can I use Titan Mars Pale instead of Ice Yellow?

The same difference applies the other way round: Titan Mars Pale is a little darker, more muted, 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.