Murderous Magenta vs Lipstick

How close are they?

ΔE 19.1, loose: different enough that you should pick on purpose. Lipstick is noticeably lighter, more saturated, warmer than Murderous Magenta.

Can I use Lipstick instead of Murderous Magenta?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Lipstick is noticeably lighter, more saturated, warmer than Murderous Magenta.

Can I use Murderous Magenta instead of Lipstick?

The same difference applies the other way round: Murderous Magenta is noticeably darker, more muted, cooler.

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.