Citron
A source of confusion is that "citron" or similar words in French (and other languages), and English are false friends, as they refer to the lemon. Indeed, into the 16th century, the English name "citron" included the lemon and perhaps the lime as well.
Orange (fruit)
The taste of oranges is determined mainly by the relative ratios of sugars and acids, whereas orange aroma derives from volatile organic compounds, including alcohols, aldehydes, ketones, terpenes, and esters. Bitter limonoid compounds, such as limonin, decrease gradually during development, whereas volatile aroma compounds tend to peak in mid– to late–season development. Taste quality tends to improve later in harvests when there is a higher sugar/acid ratio with less bitterness. As a citrus fruit, the orange is acidic, with pH levels ranging from 2.9 to 4.0.