ΔE 15.7, loose: different enough that you should pick on purpose. Transparent Brown Iron Oxide is much more saturated than Kawa Brown.
Can I use Transparent Brown Iron Oxide instead of Kawa Brown?
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Transparent Brown Iron Oxide is much more saturated than Kawa Brown.
Can I use Kawa Brown instead of Transparent Brown Iron Oxide?
The same difference applies the other way round: Kawa Brown is much 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.