Malbim: Here (verses 11-41) it lists the Giborim mentioned in Shmuel II, 23:8-39, and after this, here (11:42-47, 12:1-14) it lists others not listed there. Sefer Shmuel lists only those who were with David always. Ezra included (12:1-14) those who helped to establish him as king (but were not with him always), and others (11:42-47) who were with him always, that he found written in the king's chronicles.