The English word pronoun is used according to its literal meaning, i.e. referring only to such words that can replace nouns. Therefore "ours" is a possessive pronoun, but "our" is a possessive adjective. In German, however, both kinds of words are called Pronomen. The grammatical difference can be expressed by calling "ours" a substantivisches Pronomen and "our" an adjektivisches Pronomen.
- Pronomen in Duden online