You might drop a pinch of baking soda on the liquid--if it is vinegar or battery acid, it will fizz, water will not. If it fizzes, then wafting your hand over the liquid to get a smell of it could help you tell if it has the smell of vinegar, battery acid doesn't smell like vinegar.
A clear puddle of liquid underneath your car in the driveway would more than likely be from the air conditioner which means it is just water. You could tell right away if it was battery acid or vinegar due to the smell it would emit. Also, battery acid would most likely damage the driveway. You would want to be careful if you are going to get close enough to smell it just in case it is battery acid. Battery acid contains sulphuric acid which can be very damaging to the skin.
If it is a question relating to chemistry, perhaps it assumes ready availability of some chemicals or facilities of testing. Bur if it is a question from common everyday life, I will try to make out the substance from its smell. While water will have no smell, vinegar will have a very distinct smell. Acid will have some kind of acrid smell which I may not recognize very clearly. If some how or the other I had a means of knowing that is is only one of these three options the smell test will be good enough to identify the liquid clearly. But If I do not have these three possible options, things will be more difficult.
But then I will not just stop with the smell test. I will also try to find the source from which the liquid in the puddle has come. Once possible sources have been identified, I will match the smell of liquid in puddle with that in suspected source. If this matches, it will be a confirmation of the original smell test.
One of the first things that I would do to determine what the substance is on the driveway floor is to visually inspect it. I would look at the color, the smoothness, and how it appears in general. I could also smell it. Vinegar has a distinct smell and water has none unless it has a lot of sulfur in it.
A person could also pour baking soda onto the liquid. If it is vinegar it will fizzles and bubble. Water will not react. Battery acid will also bubble up.