ΔE 16.1, loose: different enough that you should pick on purpose. Titan Mars Pale is noticeably lighter, warmer than Ionrach Skin. They are different kinds of paint: Citadel Ionrach Skin is an opaque base/layer paint and Golden Titan Mars Pale is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Titan Mars Pale is noticeably lighter, warmer than Ionrach Skin. They are different kinds of paint.
The same difference applies the other way round: Ionrach Skin is noticeably darker, 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 Ionrach Skin on the colour wheel See Titan Mars Pale on the colour wheel
All matches: Ionrach Skin equivalents · Titan Mars Pale equivalents