T'au Light Ochre vs Sunny Skin Tone

How close are they?

ΔE 15.9, loose: different enough that you should pick on purpose. Sunny Skin Tone is a little lighter, more saturated, warmer than T'au Light Ochre.

Can I use Sunny Skin Tone instead of T'au Light Ochre?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Sunny Skin Tone is a little lighter, more saturated, warmer than T'au Light Ochre.

Can I use T'au Light Ochre instead of Sunny Skin Tone?

The same difference applies the other way round: T'au Light Ochre is a little darker, more muted, cooler.

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.