ΔE 14.5, fair: the same colour family, but not a straight swap. Transparent Brown Iron Oxide is a little darker, warmer than Aggaros Dunes. They are different kinds of paint: Citadel Aggaros Dunes is a one-coat contrast-style paint and Golden Transparent Brown Iron Oxide is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Transparent Brown Iron Oxide is a little darker, warmer than Aggaros Dunes. They are different kinds of paint.
The same difference applies the other way round: Aggaros Dunes 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.
See Aggaros Dunes on the colour wheel See Transparent Brown Iron Oxide on the colour wheel
All matches: Aggaros Dunes equivalents · Transparent Brown Iron Oxide equivalents