Halliday & Matthiessen (1999: 186-7):
Taxonomically organised qualities are often named by denominal adjectives, but they are still experientially simpler than the corresponding nouns. Consider e.g. nationality, philosophical persuasion, and biological kind: as qualities, these are classes and therefore closest to things, but their extension is still greater than that of the things that correspond to them: see Table 5(1).
Thus an Albanian always means 'a human citizen of Albania', whereas the adjective Albanian could refer to any of a large number of concrete or abstract entities: Albanian wine, Albanian literature, Albanian economy.