ΔE 15.1, loose: different enough that you should pick on purpose. Fresh Blood is noticeably lighter, cooler than Flesh Tearers Red. They are different kinds of paint: Citadel Flesh Tearers Red is a one-coat contrast-style paint and Vallejo Fresh Blood is a fluorescent or effect 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 15). Fresh Blood is noticeably lighter, cooler than Flesh Tearers Red. They are different kinds of paint.
The same difference applies the other way round: Flesh Tearers Red is noticeably darker, 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 Flesh Tearers Red on the colour wheel See Fresh Blood on the colour wheel
All matches: Flesh Tearers Red equivalents · Fresh Blood equivalents