The New American Bible (NAB) follows the more recent division of the Psalms found in the current Hebrew Bible. The Douay-Rheims Version (DRV) follows the older division of the Psalms found in the Latin Vulgate and the Greek Septuagint.
Psalm 9 in the DRV is divided into two psalms in the NAB, Psalms 9 and 10. This division causes the numbering of the subsequent psalms in the NAB to be off by one from the DRV so that Psalm 21 in the DRV is Psalm 22 in the NAB.
Other division differences:
Psalm 113 in the DRV is divided into two psalms in the NAB, Psalms 114 and 115.
Psalm 114 and 115 in the DRV are combined into one psalm in the NAB, Psalm 116.
Psalm 146 and 147 in the DRV are combined into one psalm in the NAB, Psalm 147.
