Trollslayer Orange vs Khador Red Base

How close are they?

ΔE 26.1, loose: different enough that you should pick on purpose. Khador Red Base is a little darker, much more saturated, cooler than Trollslayer Orange.

Can I use Khador Red Base instead of Trollslayer Orange?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 26). Khador Red Base is a little darker, much more saturated, cooler than Trollslayer Orange.

Can I use Trollslayer Orange instead of Khador Red Base?

The same difference applies the other way round: Trollslayer Orange is a little lighter, much 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.