The NIV was published in 1978. It may be considered a counterpart to the NEB. (The NEB is strictly a British product, while the NIV is an international product). It is more of a phrase-for-phrase translation than a word-for-word translation. The translators were generally more conservative than those who worked on the neb. I personally consider it the best phrase-for-phrase translation available today. However, its major flaw is its simplicity of language. The editors wanted to make sure it was easy to read. In achieving this goal, they often sacrificed accuracy. In the New Testament, sentences are shortened, subordination of thought is lost, and conjunctions are often deleted.
The TNIV is to the NIV what the NRSV is to the RSV. Gender-inclusive language is used, and specific terminology is clarified (e.g., instead of "the Jews," the TNIV will read "the Jewish leaders," and when "Christ" is used as a title, is substituted for "Messiah"). This is usually helpful, but such interpretations built into a translation can at times be misleading.
http://www.biblestudytools.com/bible-study/tips/choosing-a-bible-translation-11631126.html
The TNIV is to the NIV what the NRSV is to the RSV. Gender-inclusive language is used, and specific terminology is clarified (e.g., instead of "the Jews," the TNIV will read "the Jewish leaders," and when "Christ" is used as a title, is substituted for "Messiah"). This is usually helpful, but such interpretations built into a translation can at times be misleading.
http://www.biblestudytools.com/bible-study/tips/choosing-a-bible-translation-11631126.html