Ptolemy used the word geography to signify the description of the whole oekumene on mathematical principles, while chorography signified the fuller description of a particular region, and topography the very detailed description of a smaller locality.
This slender distinction was made much of by most subsequent writers until Nathanael Carpenter in 1625 pointed out that the difference between geography and chorography was simply one of degree, not of kind.
" Geography," in the sense in which he uses the term, signifies the delineation of the known world, in the shape of a map, while chorography carries out the same objects in fuller detail, with regard to a particular country.
(often separately entitled Descriptio Insularum Aquilonis; Adam's is the earliest extant reference to Vinland, c. 1070): we have also notices of Vinland in the Libellus Islandorum of Ari Frodi (c. 1120), the oldest Icelandic historian; in the Kristni Saga (repeated in Snorri Sturlason's Heimskringla); in Eyrbyggia Saga (c. 1250); in Gretti Saga (c. 1290); and in an Icelandic chorography of the 14th century, or earlier, partly derived from the famous traveller Abbot Nicolas of Thing-eyrar (j'1159).
Doubtless, however, he returned to Rome after a long sojourn in Alexandria, a fact which explains the defectiveness of his information about the countries to the east of his native land, and renders it possible for him to have made use of the " chorography " of Agrippa, a map of the Roman Empire and adjacent countries set up by order of Augustus in the Porticus Vipsaniae.
The Geography is a meagre sketch, based mainly on the Chorography of Pappus of Alexandria (in the end of the 4th century), and indirectly on the work of Ptolemy.