Tanned Flesh vs Knight-Questor Flesh

How close are they?

ΔE 15.2, loose: different enough that you should pick on purpose. Knight-Questor Flesh is noticeably darker, more saturated than Tanned Flesh.

Can I use Knight-Questor Flesh instead of Tanned Flesh?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Knight-Questor Flesh is noticeably darker, more saturated than Tanned Flesh.

Can I use Tanned Flesh instead of Knight-Questor Flesh?

The same difference applies the other way round: Tanned Flesh is noticeably lighter, more muted.

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.