Possessive pronouns ARE possessive adjectives. They are the same.

The possessive pronouns are those which describe nouns (my, your, his, her, their, our). 'My book is interesting.' 'my' is an adjective because it modifies or describes the noun 'book'. It is a possessive adjective because it tells us who the book belongs to. The possessive pronouns are those which replace a noun (mine, his, hers, ours, yours, theirs). Your car is green (possessive adjective). 'Mine' is red (possessive pronoun) 'mine' replaces 'my car' and is therefore a pronoun. It is possessive because it also tells us who owns the noun it is replacing.