1996 was the date that the New Living Translation was originally published.
2004 was the date that the second edition of the New Living Translation was published. You can read about the improvements made in this transition here.
Since the second edition of the NLT was published in 2004, the NLT Bible Translation Committee has approved three rounds of changes to the NLT text. The 2007 and 2013 changes were mostly minor textual or footnote changes resulting from queries that came from our own editors as they worked on new NLT commentaries and Bible notes, closely comparing the NLT to the original language texts. Some of the 2015 changes attempt to clarify the text for an international readership by removing language that is specific to an American context, while others seek to improve clarity and precision in other ways. Some of the changes were made as a result of helpful feedback from church leaders from across the English-speaking world who value the clarity that the NLT provides for their ministries. Additionally, the word “leper(s)” has consistently been replaced with an appropriate phrase like “man with leprosy” in order to emphasize personhood over the disability. The 2015 changes affect a total of eighty-six verses and four NLT subheads. The review process that generated these changes demonstrates the Bible Translation Committee’s continued commitment to both scholarly precision and clear communication in modern English.
Details to the 2015 updates can be found at this link.