My limited Google-fu shows both appear to be in use. Google Ngram is very puzzling, as it shows the two terms switched popularity positions. What are the differences between these two terms?
Learn English – “Swim team” vs “swimming team”
differencephrase-meaning
Related Solutions
Both "What is the difference between X and Y?" and "What are the differences between X and Y?" are grammatical and will be understood.
According to my native-speaker intuition, "What is the difference ...?" is the normal phrasing. I would only use "What are the differences ...?" if I was already pretty sure that there was more than one difference.
EDIT: Some additional cases that came up in the comments:
The labels "X" and "Y" will, of course, always be different, but that does not count as a difference between the things X and Y, and therefore is not a reason to use the plural form. The answer to "What is/are the difference/s between ice cream and ice-cream?" would be "There is none, they are the same thing."1
"What is a difference between X and Y?" is also grammatical, but it means something that one hardly ever wants to say: the speaker has deliberately refused to indicate how many differences he or she thinks there are, and no matter how many the listener thinks there are, the speaker only wants to hear about one of them. The only time I personally would use this variation is if I was writing an exam question.
"How do X and Y differ?" is an alternative phrasing that avoids the question of number altogether; unlike "What is a difference...", it carries no special connotations.
1 Consider also tomAYto versus tomAHto. You might find it helpful to read up on the use-mention distinction.
Faucet
a device with a hand-operated valve for regulating the flow of a liquid
Spigot
a faucet
the valve or plug in a faucet
Tap
a device for starting or stopping the flow of liquid in a pipe, barrel, etc.; faucet
They all can be used when you're talking about a device that starts or stops the flow of a liquid, but there are some regional variations in how they're commonly used.
In my region, faucet is used for the common household fixture that can mix hot and cold water together and control how fast the water flows.
A spigot is a single knob faucet that only has one pipe it controls, like the outdoor spigot that you connect a garden hose to.
A tap is used when there isn't a pipe, like when you tap a keg of beer, or tap a maple tree for syrup. Tap is a little unusual because it can also be the act of tapping as well as the device you use to control the flow. A tap has the sense to me of poking a hole in something that has liquid in it, and being able to keep the liquid from just gushing out with some sort of device. Faucets and spigots are plumbing, with connectors and pipes.
I know that in other areas of the US, folks use "tap" or "spigot" the way I use "faucet". We can still understand each other, so it's fine to use them as synonyms.
As mentioned in the comments, in British English, "tap" is used for all three, which makes sense because "tap" is from Old English and "faucet" and "spigot" are from Old French according to an online etymology dictionary.
Best Answer
If you compare British and American corpora, the split is more distinct. While swimming team was the more common term in both a century ago, swim team has soared in popularity since the latter half of the 20th century, and is the far more prevalent form in the U.S.:
Still, it's not difficult to find swimming team in respectable American sources like Swimming World magazine, and few would object to swimming and diving team over swim and dive team (many high school and university athletic departments combine the two sports into one program). In other words, there is no difference in meaning between a swim team and a swimming team, only in preference or familiarity.
I don't think the swing can be attributed to any one particular cause, and it isn't applicable to other sports or word pairs. Swimming coach, for example, has been more resilient in AmE vs. swim coach:
The -ing remains safely ensconced in many sports: there are far more cycling teams than cycle teams, and I do not think boxing, fishing, or cheerleading are in any danger of changing, for example. On the other hand, I'm perfectly fine with ski instructor, hunt club, skate coach, or snowboard helmet where some might insist upon the progressive forms.