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When writing an exam question, are the followings imply very different things? Does (1) imply there is only one difference? I think (2) implies there may be multiple differences, but describing only one of them is fine. I am not sure the role of the definite article here. (5) seems wrong, but one can argue for it by interpreting "difference" in a particular way?

  1. Describe the difference between A and B.
  2. Describe a difference between A and B.
  3. Describe the differences between A and B.
  4. Describe differences between A and B.
  5. Describe difference between A and B.
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2 Answers 2

up vote 3 down vote accepted

Describe the difference between A and B. There is one difference, describe it.
Describe a difference between A and B. There may be more differences, describe only one of them.
Describe the differences between A and B. There are several differences, describe them all.
Describe differences between A and B. There are several differences, describe some of them.
Describe difference between A and B. Wrong indeed

As J.R. remarks, there is some room for interpretation in the third sentence. The writer might not expect the answerer to give all the differences, but that depends on the situation.

If I ask a general open question about a subject the student should have studied, I could ask:

What are the differences between a monarchy and a republic?

I would expect you to answer the main distinctive differences about the forms of government, and not, for instance, whether during the 3rd century ad in western South America, societies resembled a monarchy more often than a republic.

However, if I gave you a text to read and I ask you

What are the difference that the author has noticed between the red and the blue phone?

I do expect you to list all the differences that are mentioned in the text.

In general, when you use the definite article (the), you indicate that you want a description of the specific thing or things you are asking about. So not just some random difference, but the difference, the one difference that exists between A and B - or the differences, the whole set of differences, all of them.

When you use the indefinite article (a or zero, no article), you are asking to describe any difference, or differences, that apply to A and B, but not the whole set of differences that might exist.

There is a little but in this:

When someone refers to the difference between A and B, it usually does not imply there is only one difference! The difference, often with the emphasized in some way, spoken or written, means the most important difference.

Suppose I write an article about two new phones that come out. They have slightly different prices, they have a slightly different performance and the other one lasts half an hour longer on the battery.

But the difference between phone A and B is the screen: A has a 2 inch VGA-resolution screen, whereas B sports a state-of-the-art 42 inch WTFBBQXSVGA-resolution screen.

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I agree with this answer, except I think there is a little room for interpretation on the third one. Describe the differences between A and B could mean, There are several differences; describe the more significant ones, particularly if the student is not expected to write more than a page or so. – J.R. Jun 18 '14 at 9:13
@ J.R. - good point, I added a bit to my answer. – oerkelens Jun 18 '14 at 9:20

To ground this question in a context, I'll assume these are exam questions which must be answered within a limited amount of time and length. This will make it "easier to talk about" without being too abstract, but the answers can be expanded to other scenarios.

  1. Describe the difference between A and B. The definite article "the" indicates that there is a single, primary difference. However, it could be a complex singularity. For example, "Describe the difference between red and yellow" might simply be "they are two different colors" but "describe the difference between democracy and theocracy" could be either a simple statement, an essay, or an entire book.

  2. Describe a difference between A and B. The indefinite article "a" indicates a more concise singularity. Since you have trouble with this, I'll expand it for you as "Among the multiple differences that there are (or may be) between A and B, describe one of them."1 There are multiple differences, and you are being asked to choose only one. This could still be a complicated difference if posed as an essay question, but if the question was "describe a difference between democracy and theocracy", the focal difference (the one of your choice) would be stated in a single sentence. From there, it could be expanded upon. This type of question is useful to help students limit the scope of their answer to a single topic. In a test situation, of course, you would typically want to choose one of the primary differences.

    On the other hand, a creative approach might zero in on a less-primary (which is probably the best choice if you can do this) or even an esoteric difference that may not be generally obvious. These are often interesting since they delve into less explored territory and require more thought, creativity, logic, and development. In fact, I just did something similar with my just-completed-and-posted question in which I ask about a very specific non-primary difference between between and among..

  3. Describe the differences between A and B. The plurality differences is asking for a multitude of differences. As an essay question, one would have to consider perhaps a few of the main differences, and the analysis would not be able to go into as much depth on each difference. For example, in a typical test situation, one might consider several primary differences and dedicate one paragraph to each.

  4. Describe differences between A and B. The lack of the article "the" may simply be an elliptical construction. It could be interpreted as Describe [the | some | all] differences between A and B. Or it may subtly indicate that the author of the question doesn't have (or doesn't want to convey) any notion or expectation that there is any difference. This requires the student to resolve the ambiguity as they see fit or as it may be most relevant.

  5. Describe difference between A and B. This form is ungrammatical relative to formal standard English. However, questions like this, appearing on a test (perhaps quickly prepared by a teacher or a teacher's assistant) could simply be another terse elliptical construction of Describe the difference between A and B. In my experience, sentences like this are more often found in the sciences, especially mathematics and computer science. This form contains a bit more ambiguity that the student must address in a manner best applicable to the question as well as the time and length limitations of the answer.

Note on resolving ambiugity: Ambiguity can be resolved by asking for clarification, if that's possible. Also, ambiguity can be resolved by the context of the question (is there an obvious interpretation) and environment (testing conditions; perhaps there is no right answer and you simply need to complete this and move on to the next one). Thirdly, ambiguity can be resolved by your own creative explicit or implicit manner in how you answer the question. For example, I reduced ambiguity by asserting my answer would be in the context of taking a test!

1. Many language learners have difficulty with the definite and indefinite articles "a" and "the". For more info, check definite indefinite articles and Google Search: definite indefinite articles a the

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On #5, if I was aiming for a more terse construction, I'd probably write: Differentiate between A and B. I think the ungrammatical form is best left off an exam, lest the students get mentally sidetracked by the ungrammatical English. – J.R. Jun 18 '14 at 9:16
I noticed that #5 seems "less grammatical" than #4 (based on my native speaker intuition). But the only difference is plurality. Can anyone confirm/rebut/explain? Are they both ungrammatical? Is #5 worse than #4? Etc. – CoolHandLouis Jun 18 '14 at 9:50
#4 is okay; #5 is not. Articles are not needed with plural or mass nouns, but need to be present in the singular (otherwise, we sound like Tarzan). Compare: Don't forget to take towels to the beach. (ok) Don't forget to take the towels to the beach. (ok) Don't forget to take a towel to the beach. (ok) Don't forget to take towel to the beach. (NOT ok) Or: Bring donuts to the meeting. (ok) Bring the donuts to the meeting. (ok) Bring a donut to the meeting. (ok) Bring donut to the meeting. (NOT ok) – J.R. Jun 18 '14 at 16:50
Mmmm.... donuts. Huh? [Joke reference to Homer Simpson from TV show The Simpsons who's mind always goes blank when thinking about donuts.] – CoolHandLouis Jun 18 '14 at 20:15

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