What is the difference between using noun as premodifier (of a head noun) and pa...

For example, what is the difference between

• race car vs

• racing car;

• cook oil vs

• cooking oil.

There are many ways of making a compound noun. Often you just need to know (look up some options in a dictionary, do a web search, ask a chatbot, etc).

There are some guidelines you can use.

If something is associated with an activity, then if there's a noun for that activity, you use the noun (e.g. with names of sports: snooker cue, football boots).

For other activities it's common to make a compound noun with an -ing verb as premodifier: fishing rod, driving gloves, walking stick, paving stone, washing machine, fencing mallet. But you need to be aware that something like "racing car" could be a compound noun meaning a car built for racing, or a noun phrase with "racing" a participle modifying "car", meaning a car which is currently racing.

If something is associated with an object (substance, foodstuff, etc), you can use a simple noun: wine bottle, fish knife, bread board, carpet tack. This is particularly the case if the preceding noun differentiates between different types of thing: soup spoon vs tea spoon.

If something is associated with a person, then often 's is used after the person's job/role/etc, e.g. ploughman's lunch, fisherman's sweater, chef's knife, hunter's moon.

But none of these rules are infallible. "Race car" is more common in the US and "racing car" is more usual in the UK. "Cook oil" doesn't really fit any of the above rules, and "cooking oil" is preferred.