structural:reformatting, stylistic:tone
Book order

The Jewish textual tradition never finalized the order of the books in Ketuvim. The Talmud gives their order as Ruth, Psalms, Job, Proverbs, Ecclesiastes, Song of Songs, Lamentations, Daniel, Scroll of Esther, Ezra, Chronicles. This order is roughly chronological (assuming traditional authorship).

In Tiberian Masoretic codices (including the Aleppo Codex and the Leningrad Codex), and often in old Spanish manuscripts as well, the order is Chronicles, Psalms, Job, Proverbs, Ruth, Song of Songs, Ecclesiastes, Lamentations, Esther, Daniel, Ezra. This order is more thematic (e.g. the megillot are listed together).