ΔE 16.9, loose: different enough that you should pick on purpose. Warlord Purple is a little darker, much more saturated than Elder Flower.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Warlord Purple is a little darker, much more saturated than Elder Flower.
The same difference applies the other way round: Elder Flower is a little lighter, much more muted.
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 Elder Flower on the colour wheel See Warlord Purple on the colour wheel
All matches: Elder Flower equivalents · Warlord Purple equivalents