Orange Tone vs Umber Wash

How close are they?

ΔE 54.5, loose: different enough that you should pick on purpose. Umber Wash is a little lighter, much more muted than Orange Tone.

Can I use Umber Wash instead of Orange Tone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 55). Umber Wash is a little lighter, much more muted than Orange Tone.

Can I use Orange Tone instead of Umber Wash?

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