For example, what is the difference between
race car vs
racing car;
cook oil vs
cooking oil.
For example, what is the difference between
race car vs
racing car;
cook oil vs
cooking oil.
Normally you would find as much difference in the compound word as in the noun-'ing-suffixed' pair. e.g. 'cool car' and 'cooling car'. Take another pair, 'skid car' and 'skidding car'. In your example both are NP. In the first the proper 'common noun' form, in the second the -ing suffixed form is modifying the second noun.
For example, what is the difference between • race car vs • racing car;
They are identical constructions = NP1 + NP2. = NP2 associated contextually with NP1.
It happens that race is a noun and racing is a gerund (not a participle).
Race car = a car that is contextually associated with a race
Racing car = a car that is contextually associated with racing
To take Edwin Ashworth’s examples:
'fish scale' a scale that is contextually associated with fish
'fishing rod' a rod that is contextually associated with fishing
'Fly paper' - a paper that is contextually associated with flies
'flying lessons' – lessons that are contextually associated with flying