Faded Purple vs Saddle Brown

How close are they?

ΔE 15.5, loose: different enough that you should pick on purpose. Saddle Brown is a little darker, warmer than Faded Purple.

Can I use Saddle Brown instead of Faded Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Saddle Brown is a little darker, warmer than Faded Purple.

Can I use Faded Purple instead of Saddle Brown?

The same difference applies the other way round: Faded Purple is a little lighter, cooler.

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.