Actually the answer to that question is more complicated than you would think at first.
The New World Translation was released in six stages from 1950 though 1960:
New World Translation of the Christian Greek Scriptures 1950
New World Translation of the Hebrew Scriptures vol. I 1953
New World Translation of the Hebrew Scriptures vol. II 1955
New World Translation of the Hebrew Scriptures vol. III 1957
New World Translation of the Hebrew Scriptures vol. IV 1958
New World Translation of the Hebrew Scriptures vol. V 1960
On June 23, 1961, one compact version (1466 pages) was released. Although JW literature today claims that Witnesses were "overjoyed" with this realease, many of them were disappointed with the omision of the marginal cross-references, footnotes and appendix that they had become used to.
In 1963, two other editions were released. One was a pocket sized edtion and the other was the "Large print original edition." Basically this was all six original volumes bound together in their original format. (3600+ pages) More recent JW publications (e.g. The Proclaimers book) refer to this as the "Students Edtion." However it is often colloquially known among collectors as the "Fat Boy."
(Original 1963 and 1961 NWT's)
The "Fat Boy" was only published for a few years, and today they are fairly rare. The slimmer 1961 edtion subsequently became the standard Bible of most JW's. In 1962, it became available in either the Standard (Green hardcover) and Deluxe (Black or maroon soft cover) bindings.
The New World Translation has been revised several times since 1961. It was revised both in 1970 and again 1971 with the release of a large print edition, but the binding remained the same for standard size Bibles.
In 1981, the 1971 revision was given a new binding and the copyright was renewed. This was the end of the "Green Bible" as standard and Deluxe bindings were both black. The interesting maps on the inside covers (The Ancient World & Paul's Jouneys) with lattitude and longitude, cultural figures, whales and a dinosaur were also replaced.
However this Bible (1971 edition + 1981 binding) was only published for a few years and these are also becoming somewhat uncommon today. In 1984, the New World Translation was again revised, the copyright was renewed, and it was given a slightly different binding in both standard and large print edtions. Cross references and footnotes were added. (or more accurately, added back)
(1981 and 1984 NWT's -- Deluxe bindings)
So when it comes to the textual differences between these Bibles you can see there is not a simple answer (e.g. Green vs. Black) because we are dealing with multiple revisions and multiple bindings and no concise listing of all the differences between all the edtions.
On page 1445 and 1446 of 1971 editions a list of changes is given. These include words replaced, words transposed, words added, words deleted, etc. Whether these changes are "major" or "minor" largely depends upon your religious beliefs. (or lack thereof)
Most of them appear minor to me. The handful of things that strike me as objectionable in the NWT (e.g. John 17:3) have been there right from the beginning.
Tom
