Lollipop Magenta vs Devil Red

How close are they?

ΔE 17.1, loose: different enough that you should pick on purpose. Devil Red is noticeably lighter, more saturated than Lollipop Magenta.

Can I use Devil Red instead of Lollipop Magenta?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Devil Red is noticeably lighter, more saturated than Lollipop Magenta.

Can I use Lollipop Magenta instead of Devil Red?

The same difference applies the other way round: Lollipop Magenta is noticeably darker, 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.