ΔE 7.7, close: similar, with a visible difference side by side. Mid Feldgrau is a little lighter, more saturated than RLM 73.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Mid Feldgrau is a little lighter, more saturated than RLM 73.
The same difference applies the other way round: RLM 73 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 RLM 73 on the colour wheel See Mid Feldgrau on the colour wheel
All matches: RLM 73 equivalents · Mid Feldgrau equivalents