Autumn Sage vs Grey Teal

How close are they?

ΔE 16.3, loose: different enough that you should pick on purpose. Grey Teal is noticeably darker, more muted, cooler than Autumn Sage.

Can I use Grey Teal instead of Autumn Sage?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Grey Teal is noticeably darker, more muted, cooler than Autumn Sage.

Can I use Autumn Sage instead of Grey Teal?

The same difference applies the other way round: Autumn Sage is noticeably lighter, 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.