Shifting Sands vs Ruby Red

How close are they?

ΔE 20.8, loose: different enough that you should pick on purpose. Ruby Red is noticeably lighter, cooler than Shifting Sands.

Can I use Ruby Red instead of Shifting Sands?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Ruby Red is noticeably lighter, cooler than Shifting Sands.

Can I use Shifting Sands instead of Ruby Red?

The same difference applies the other way round: Shifting Sands 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.