Dark Soviet Khaki vs Asheth Grey

How close are they?

ΔE 16.8, loose: different enough that you should pick on purpose. Asheth Grey is a little darker, more muted than Dark Soviet Khaki.

Can I use Asheth Grey instead of Dark Soviet Khaki?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Asheth Grey is a little darker, more muted than Dark Soviet Khaki.

Can I use Dark Soviet Khaki instead of Asheth Grey?

The same difference applies the other way round: Dark Soviet Khaki is a little lighter, more saturated.

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.