Bloodreaver Flesh vs Burnt Sienna

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Burnt Sienna is more saturated than Bloodreaver Flesh.

Can I use Burnt Sienna instead of Bloodreaver Flesh?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Burnt Sienna is more saturated than Bloodreaver Flesh.

Can I use Bloodreaver Flesh instead of Burnt Sienna?

The same difference applies the other way round: Bloodreaver Flesh is 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.