Moody Mauve vs Twilight Rose

How close are they?

ΔE 27.7, loose: different enough that you should pick on purpose. Twilight Rose is noticeably darker, much more muted than Moody Mauve.

Can I use Twilight Rose instead of Moody Mauve?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Twilight Rose is noticeably darker, much more muted than Moody Mauve.

Can I use Moody Mauve instead of Twilight Rose?

The same difference applies the other way round: Moody Mauve is noticeably lighter, much more saturated.

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.