RSV is Revised Standard Version. It is a revised edition of a particular Bible.
NRSV - New Revised Standard Version of the Bible
Richard E. Whitaker has written: 'The Eerdmans analytical concordance to the Revised Standard Version of the Bible' -- subject(s): Bible, Biblical Greek language, English Concordances, Glossaries, vocabularies, Hebrew language, Latin language, Revised standard, Revised Standard
RSV stands for "Revised Standard Version," which was published in 1952. According to its own preface: "The Revised Standard Version of the Bible is an authorized revision of the American Standard Version, published in 1901, which was a revision of the King James Version, published in 1611."
New Revised Standard Version (NRSV)
The New Standard Revised Version
The HarperCollins Study Bible - New Revised Standard Version
The ESV or English Standard Version of the Christian Bible was last revised in 2011. Before 2011, it was revised in 2007 and 2001. This version is good if a person has trouble reading the other version.
"RSV" stands for Revised Standard Version.
Revised English Bible was created in 1989.
Catholics typically read the New American Bible (NAB) or the Revised Standard Version Catholic Edition (RSV-CE) of the Bible.
You have asked about a NSAB Bible, however I think you are referring to the NASB Bible which is abbreviated for "New American Standard Bible".This is an updated version which was translated in 1995 from the ASB (American Standard Bible) of 1901. A more literal and modern, up-to-date version.The King James Bible was authorised and translated in 1611. Today, its words are considered archaic, old fashioned language and out of date in the 21st century.So different Bible societies and Bible scholars from various countries decided to review and translate the KJB (or KJV) into a more contemporary style of language suited to the culture of its country. The King James Version despite its archaic language is still very popular but it too has been revised and translated into modern day language.