"Apples and oranges" refers to the idiom "comparing apples and oranges" or "apples to oranges", which is used to indicate that two items or groups of items have not been validly compared. The idiom evokes the apparent differences between items which are popularly thought to be incomparable or incommensurable, such as apples and oranges. The idiom may also be used to indicate that a false analogy has been made between two items, such as where an "apple" is faulted for not being a good "orange". Conversely, where the comparison or analogy is valid, the idiom will usually take the form "comparing apples with apples".
The idiom is not unique. In Quebec French it may take the form "comparer des pommes avec des oranges" while in European French the idiom hesitates between "additionner des carottes et..." something else which can be "des pommes de terre", "des navets" or "des choux". In Latin American Spanish usually is "comparar papas y boniatos" or "comparar peras con manzanas". In some other languages the term for "orange" derives from "apple", suggesting not only that a direct comparison between the two is possible, but that it is implicitly present in their names. Fruit other than apples and oranges can also be compared; for example, apples and pears are compared in Danish, Dutch, German, Spanish, Swedish, Czech, Romanian, Slovene, Luxembourgish and Turkish. However, apples are actually more closely related to pears — both are rosaceae — than to oranges. In fact, in the Spanish-speaking world, a common idiom is sumar peras con manzanas - that is, "to add pears and apples". The same thing applies in Romanian where a popular idiom is a aduna merele cu perele - that is again, "to add apples and pears".
Some languages use completely different items, such as Serbian "Поредити бабе и жабе" (comparing grandmothers and toads) or Romanian "baba şi mitraliera" (the grandmother and the machine gun) or "vaca şi izmenele" (the cow and the longjohns) or "tiganul si carioca" (the gypsy and the marker), while some languages compare dissimilar properties of dissimilar items. For example, the equivalent Danish idiom, "Hvad er højest, Rundetårn eller et tordenskrald?" translates word-by-word as "What is highest, the Round Tower or the volume of a thunderclap?" In British English, the phrase chalk and cheese means the same thing as apples and oranges. In Argentina, a common question is "En qué se parecen el amor y el ojo del hacha?" which translates into "What do love and the eye of an axe have in common?" and emphasizes dissimilarity between two subjects; in Colombia, a similar (though more rude) version is common: "confundir la mierda con la pomada" - literally, to confuse shit with ointment.
A number of more exaggerated comparisons are sometimes made, in cases in which the speaker believes the two objects being compared are radically different beyond reproach. For example "oranges to orangutans" "apples to dishwashers" and so on. In English, different fruits, such as pears, plums, or lemons are sometimes substituted with "oranges" in this context.
Various scholars have questioned the premise of the incomparable nature of apples and oranges, both in serious publications and in weblogs and spoofs (see below). These criticisms of the idiom, however, tend to assume that "you cannot compare apples and oranges" is a descriptive statement capable of logical or scientific counter-example, without addressing the possibility of interpreting the idiom as a normative statement (meaning something such as "it's not fair to judge apples and oranges by the same criteria").
At least two tongue-in-cheek scientific studies have been conducted on the subject, each of which concluded that apples can be compared to oranges fairly easily and on a low budget and the two fruits are quite similar. The first study, conducted by Scott A. Sandford of the NASA Ames Research Center, used spectrometry to analyze both apples and oranges. The study, which was published in the Annals of Improbable Research, concluded: "[...] the comparing apples and oranges defense should no longer be considered valid. This is a somewhat startling revelation. It can be anticipated to have a dramatic effect on the strategies used in arguments and discussions in the future.
A second study, written by Stamford Hospital's surgeon-in-chief James Barone and published in the British Medical Journal, noted that the phrase "apples and oranges" was appearing with increasing frequency in the medical literature, with some notable articles comparing "Desflurane and propofol" and "Salmeterol and ipratropium" to "apples and oranges". The study also found that both apples and oranges were sweet, similar in size, weight, and shape, that both are grown in orchards, and both may be eaten, juiced, and so on. The only significant differences found were in terms of seeds (the study used seedless oranges), the involvement of Johnny Appleseed, and color.
The Annals rejoined that its "earlier investigation was done with more depth, more rigour, and, most importantly, more expensive equipment" than the British Medical Journal study.
While references to "comparing" apples and oranges is often a rhetorical device, references to "adding" apples and oranges are made in the case of teaching students the proper uses of units. Here, the admonition not to "add apples and oranges" refers to the requirement that two quantites with different units may not be combined by addition, although may always be combined by multiplication, so that "multiplying apples and oranges" is allowed — see dimensional analysis. Similarly, the concept of this distinction is often used metaphorically in elementary algebra.
The admonition is really more of a mnemonic, since in general counts of objects have no intrinsic unit and, for example, a number count of apples may be dimensionless or have dimension "fruit" — in either of these two cases, apples and oranges may indeed be added.
The expression is used to stress the impossibility of comparing values of different kinds, what is precisely what business finance people need to do. There is a business simulation, called Apples & Oranges and created by Celemi, that uses this metaphor to help people companies to understand basic fınance. The model of this board-based business simulation is deployed with different scenarıos: for manufacturing, services, retail, and even for learning EVA.
In Dutch, sweet oranges are called sinaasappel, which is derived from "China's apple". The Latvian apelsīns, Icelandic appelsína, Swedish apelsin, Finnish appelsiini, Russian апельсин (apelsin) and North-German Apfelsine share similar etymology.