Possessive pronouns show ownership or belonging and replace a previously mentioned noun. They are "mein," "dein," "sein," "ihr," "unser," "euer," "ihr," and the declined forms (they always have to be declined).
⇒ Possessive Determiner, because a noun comes after it. It's like an article.
⇒ Possessive Pronoun, because there is no noun. The possessive pronoun acts like a noun.
This difference is important, because the declension is different for the two parts of speech.
„Wem gehört der Ball?“ (Gender = masculine)
The declension is similar to declension of possessive determiners.
But: Pronouns always take the ending of the definite article, including in the nominative case (m/n) and accusative case (m)
As a placeholder for a previously mentioned noun, when we want to express who "owns" that noun / what the noun belongs to.
Possessive pronouns are most often used after a question asking who something belongs to. If we repeat the noun, it’s not a pronoun anymore. Instead, it is a possessive determiner („Das ist mein Auto!“ ).