ΔE 11.8, fair: the same colour family, but not a straight swap. Pine Hollow Shade is noticeably darker, warmer than Aggressor Blue FS 35109. They are different kinds of paint: AK Interactive Aggressor Blue FS 35109 is an opaque base/layer paint and Army Painter Pine Hollow Shade is a wash/shade, 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 12). Pine Hollow Shade is noticeably darker, warmer than Aggressor Blue FS 35109. They are different kinds of paint.
The same difference applies the other way round: Aggressor Blue FS 35109 is noticeably 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 Aggressor Blue FS 35109 on the colour wheel See Pine Hollow Shade on the colour wheel
All matches: Aggressor Blue FS 35109 equivalents · Pine Hollow Shade equivalents