ΔE 9.9, close: similar, with a visible difference side by side. Battleship Grey is a little darker, more saturated, cooler than Sword Grey. They are different kinds of paint: AMMO by Mig Sword Grey is an opaque base/layer paint and Army Painter Battleship Grey is a one-coat contrast-style paint, so they won’t behave the same on the model even where the colour is close.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Battleship Grey is a little darker, more saturated, cooler than Sword Grey. They are different kinds of paint.
The same difference applies the other way round: Sword Grey is a little lighter, more muted, 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 Sword Grey on the colour wheel See Battleship Grey on the colour wheel
All matches: Sword Grey equivalents · Battleship Grey equivalents