Clear Blue vs Imperial Blue

How close are they?

ΔE 16.8, loose: different enough that you should pick on purpose. Imperial Blue is noticeably lighter, more saturated than Clear Blue.

Can I use Imperial Blue instead of Clear Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Imperial Blue is noticeably lighter, more saturated than Clear Blue.

Can I use Clear Blue instead of Imperial Blue?

The same difference applies the other way round: Clear Blue 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.