Cosmic Dust vs Twin Suns Yellow

How close are they?

ΔE 20.5, loose: different enough that you should pick on purpose. Twin Suns Yellow is much more muted, cooler than Cosmic Dust.

Can I use Twin Suns Yellow instead of Cosmic Dust?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Twin Suns Yellow is much more muted, cooler than Cosmic Dust.

Can I use Cosmic Dust instead of Twin Suns Yellow?

The same difference applies the other way round: Cosmic Dust is 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.