Categorization vs. classification

Most people consider that the two words categorization and classification are synonyms, and use them interchangeably. However, there is a subtle difference in meaning between those two words, according to Le Grand Dictionnaire Terminologique, i.e. the dictionnary created by the Office québecquois de la langue française (Québec institute of French language), in Canada. According to their many definitions of the French words catégorisation and classification, we can identify two criteria:

  • order or no order: On one hand, a categorization does not impose an order between categories: categories are names, labels, that can be arbitrarily chosen. For instance, it makes no sense to define an order between “smokers” and “non-smokers”, which makes them categories, not classes. On the other hand, a classification defines an order between classes. For instance, in geology, classifications of animals and vegetals define a hierarchy (order) of groups (classes) of individuals that have common properties.
  • qualitative or quantitative: On one hand, in a categorization, the criteria used to decide in which category an object is put, are qualitative criteria.
    On the other hand, in a classification, the criteria are quantitative criteria, i.e. it corresponds to measures that can be made on objects to classify.

However, even if strictly speaking categorizations and classifications are different according to those two criteria, in practice both words are used as synonyms. This can even be demonstrated by the fact that definitions of catégorisation in Le Grand Dictionnaire Terminologique use terms related to classification, and vice-versa.