ΔE 25.5, loose: different enough that you should pick on purpose. Umber Wash is noticeably lighter, more muted, warmer than Agrax Earthshade.
✓ Two Thin Coats comparison chart lists these two as equivalents.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Umber Wash is noticeably lighter, more muted, warmer than Agrax Earthshade.
The same difference applies the other way round: Agrax Earthshade is noticeably darker, more saturated, 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.
See Agrax Earthshade on the colour wheel See Umber Wash on the colour wheel
All matches: Agrax Earthshade equivalents · Umber Wash equivalents