Bootstrap Leather vs US Earth Yellow

How close are they?

ΔE 15.2, loose: different enough that you should pick on purpose. US Earth Yellow is noticeably lighter, more muted than Bootstrap Leather.

Can I use US Earth Yellow instead of Bootstrap Leather?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). US Earth Yellow is noticeably lighter, more muted than Bootstrap Leather.

Can I use Bootstrap Leather instead of US Earth Yellow?

The same difference applies the other way round: Bootstrap Leather is noticeably darker, 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.