Inktense Olive vs Smoke Ink

How close are they?

ΔE 19.8, loose: different enough that you should pick on purpose. Smoke Ink is a little lighter, more muted than Inktense Olive.

Can I use Smoke Ink instead of Inktense Olive?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Smoke Ink is a little lighter, more muted than Inktense Olive.

Can I use Inktense Olive instead of Smoke Ink?

The same difference applies the other way round: Inktense Olive is a little darker, 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.