Underhive Ash vs Whitecap Beige

How close are they?

ΔE 16.1, loose: different enough that you should pick on purpose. Whitecap Beige is noticeably lighter, warmer than Underhive Ash.

Can I use Whitecap Beige instead of Underhive Ash?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Whitecap Beige is noticeably lighter, warmer than Underhive Ash.

Can I use Underhive Ash instead of Whitecap Beige?

The same difference applies the other way round: Underhive Ash is noticeably darker, 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.