Cypress Brown vs Light Umber

How close are they?

ΔE 7.4, close: similar, with a visible difference side by side. Light Umber is a little darker, cooler than Cypress Brown.

Can I use Light Umber instead of Cypress Brown?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Light Umber is a little darker, cooler than Cypress Brown.

Can I use Cypress Brown instead of Light Umber?

The same difference applies the other way round: Cypress Brown is a little lighter, 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.