هَذَا كِتَابِي.
Meaning: This is my book.
Parsing: hādhā is the subject of the nominal sentence; kitābī is its predicate, with a nominative case ending understood before the speaker’s yāʾ; -ī is the attached possessive complement in the genitive position.
هَذَا كِتَابُهُ.
Kitābu is the nominative predicate and mudāf; -hu is the genitive mudāf ilayh.