ΔE 8.8, close: similar, with a visible difference side by side. Leather Brown is a little lighter, more saturated than XV-88.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Leather Brown is a little lighter, more saturated than XV-88.
The same difference applies the other way round: XV-88 is a little 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.
See XV-88 on the colour wheel See Leather Brown on the colour wheel
All matches: XV-88 equivalents · Leather Brown equivalents