Squig Orange vs Mica Red

How close are they?

ΔE 18.5, loose: different enough that you should pick on purpose. Mica Red is noticeably darker, more saturated, cooler than Squig Orange.

Can I use Mica Red instead of Squig Orange?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Mica Red is noticeably darker, more saturated, cooler than Squig Orange.

Can I use Squig Orange instead of Mica Red?

The same difference applies the other way round: Squig Orange is noticeably lighter, more muted, 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.