ΔE 30.7, loose: different enough that you should pick on purpose. Unbleached Titanium is noticeably lighter, much more saturated than Matt Grey Primer.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 31). Unbleached Titanium is noticeably lighter, much more saturated than Matt Grey Primer.
The same difference applies the other way round: Matt Grey Primer is noticeably darker, 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 Matt Grey Primer on the colour wheel See Unbleached Titanium on the colour wheel
All matches: Matt Grey Primer equivalents · Unbleached Titanium equivalents