An allegory is a story which, when interpreted, discloses a symbolic meaning; an interpretative method which treats texts in these terms.
For other forms of figurative language, use the figure-of-speech tag.
"Allegory" and "parable" may have some intersection, but "allegory" typically is characterized by a story in which each element (or most elements) have a symbolic or representative function. For an orientation to the allegory in literature, see "Allegory" at the Literary Devices website.
"Allegorical interpretation" applies this mode of reading to texts which may not be themselves allegorical. On this, see e.g. Morton W. Bloomfield, "Allegory as Interpretation" New Literary History 3 (1972): 301-17.
