Polygonia comma form of comma is frequently confused with the dark form of the question mark ("P. interrogationis"), but the two can readily be distinguished by the shape of the comma mark on the underside. The pale form is easily confused with the satyr comma ("P. satyrus"), which usually occurs north and west of the eastern comma's range. They can be distinguished by the upperside color, which is orange brown in the comma and tawny yellowish brown in "P. satyrus"; by the underside pattern, which tends to be mottled in the comma but appears to be more longitudinally streaked in "P. satyrus";
Comma distinguish it from the Arabic diacritic "" (), representing the vowel , which is similarly comma-shaped. In Arabic texts, Western-styled comma () is used as a decimal point. Reversed comma () is used in Sindhi when written in Arabic script. It is different from the standard Arabic comma. Hebrew script is also written from right to left. However, Hebrew punctuation includes only a regular comma (). Dravidian languages such as Tamil, Telugu, Kannada, and Malayalam also use the punctuation mark in similar usage to that of European languages with similar spacing. In the common character encoding systems Unicode and ASCII,