ΔE 13.0, fair: the same colour family, but not a straight swap. Gray FS36622 is much more saturated than Wrack White.
Can I use Gray FS36622 instead of Wrack White?
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Gray FS36622 is much more saturated than Wrack White.
Can I use Wrack White instead of Gray FS36622?
The same difference applies the other way round: Wrack White is 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.