It’s easy to confuse these two sets of words because they are very similar but perform different functions.
- POSSESSIVE ADJECTIVE
As the name says, it’s an adjective which means it modifies a noun, and that noun must be expressed.
This is my book. That is her car. Their house is beautiful.
- POSSESSIVE PRONOUNS
As it’s a pronoun it replaces the noun in a clause AND shows possession.
This book is mine. That car is hers. Our house is not as beautiful as theirs.
If you have any questions or doubts, please ask in the comments or send me a private message.