Possessive Pronoun are pronouns that indicate possession
It shows that something belongs to someone.
It can be used without nouns.
E.g: His, hers, their, yours.
Possessive Adjective is also used to show possession but it is always followed by a noun.
For eg.
Your phone, His cars, my brother, his dog, etc
This is my car. Where is yours?
In this sentence, My Car is Possessive Adjective and Yours is Possessive Pronoun