ΔE 18.5, loose: different enough that you should pick on purpose. Orange Rust is noticeably lighter, more muted, warmer than Molten Lava.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Orange Rust is noticeably lighter, more muted, warmer than Molten Lava.
The same difference applies the other way round: Molten Lava is noticeably darker, more saturated, cooler.
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 Molten Lava on the colour wheel See Orange Rust on the colour wheel
All matches: Molten Lava equivalents · Orange Rust equivalents