Agrellan Badland vs Raw Sienna

How close are they?

ΔE 26.6, loose: different enough that you should pick on purpose. Raw Sienna is noticeably lighter, much more saturated than Agrellan Badland.

Can I use Raw Sienna instead of Agrellan Badland?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). Raw Sienna is noticeably lighter, much more saturated than Agrellan Badland.

Can I use Agrellan Badland instead of Raw Sienna?

The same difference applies the other way round: Agrellan Badland is noticeably darker, much 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.