ΔE 17.8, loose: different enough that you should pick on purpose. Sanguine Highlight is a little darker, cooler than Poppy Red. They are different kinds of paint: Army Painter Poppy Red is a one-coat contrast-style paint and Formula P3 Sanguine Highlight is an opaque base/layer 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 18). Sanguine Highlight is a little darker, cooler than Poppy Red. They are different kinds of paint.
The same difference applies the other way round: Poppy Red is a little lighter, warmer.
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 Poppy Red on the colour wheel See Sanguine Highlight on the colour wheel
All matches: Poppy Red equivalents · Sanguine Highlight equivalents