which of the following sentences is even more correct?
- There is a slow moving vehicle ahead.
Or
- there is a slowly moving vehicle ahead.
What is the difference between them.
To me, the second one sounds more correct as “slowly” modify moving, on the other hand the first one sound awkward as “slow” is modifying the the gerund “moving”. It means adjective cannot modify gerund, moving.
They are both correct and mean almost the same thing, but with a very slight difference.
There is a slow-moving vehicle ahead.
By using the compound adjective "slow-moving," you are implying that moving slowly is an intrinsic property of the vehicle. It's moving slowly right now because it is the type of vehicle that usually moves slowly (e.g., a garbage truck).
There is a slowly moving vehicle ahead.
By using the adverb "slowly," you are really only describing the movement right now and nothing about its habitual behavior. Maybe it's an ordinary car that just happens to be moving slowly at the moment because the driver is texting on his phone or something.
Which one is correct will depend on the situation and the type of vehicle you are talking about.
In the first sentence, slow is adjective which says something about the vehicle, i.e. it is a slow vehicle. Suppose we changed the sentence a bit, then it would be clearer:
There is a large reversing vehicle ahead.
Then it's clear that large says something about the vehicle, whereas reversing says something about the vehicle.
In the second sentence, slowly is an adverb which says something about moving, i.e. it is moving slowly.
You probably want to say that there is a vehicle ahead which is moving slowly, so you should choose the last sentence:
there is a slowly moving vehicle ahead.
The correct answer is
There is a slow moving vehicle ahead.
it meaning the vehicle is moving slowly down the street, whereas
There is a slowly moving vehicle ahead.
can mean that the actions of the vehicle are slow, for example a street cleaning machine, and its slow movement may be interpreted to be causing the vehicle to move down the street slowly.
For example
The spider slowly moved across the table
The spider's movements were slow, it's legs moved slowly, and implicitly the spider crossed the table slowly also.
