Red Ink vs Ink Magenta

How close are they?

ΔE 36.4, loose: different enough that you should pick on purpose. Ink Magenta is noticeably darker, more muted, cooler than Red Ink.

Can I use Ink Magenta instead of Red Ink?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 36). Ink Magenta is noticeably darker, more muted, cooler than Red Ink.

Can I use Red Ink instead of Ink Magenta?

The same difference applies the other way round: Red Ink is noticeably lighter, more saturated, 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.