Medium Magenta vs Pink

How close are they?

ΔE 15.1, loose: different enough that you should pick on purpose. Pink is a little darker, much more muted than Medium Magenta.

Can I use Pink instead of Medium Magenta?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Pink is a little darker, much more muted than Medium Magenta.

Can I use Medium Magenta instead of Pink?

The same difference applies the other way round: Medium Magenta is a little 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.