Rakarth Flesh vs Bastion Grey

How close are they?

ΔE 20.1, loose: different enough that you should pick on purpose. Bastion Grey is noticeably darker, more saturated, cooler than Rakarth Flesh.

Can I use Bastion Grey instead of Rakarth Flesh?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Bastion Grey is noticeably darker, more saturated, cooler than Rakarth Flesh.

Can I use Rakarth Flesh instead of Bastion Grey?

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