Summary
The Good News is a more developed *descendant* of the Today's English Version (TEV). When the Good News was "born", it was identical to the TEV. They then did additional work on the translation and added the Apocrypha.
Detailed Explanation
Today's English Version, originally published only as a New Testament in 1969 (the OT was completed by 1976) became known as the Good News Bible (GNB). In 1992, the TEV went through a translation revision, and the United Bible Societies (UBS) then released "The Good News Bible in Today's English Version" second edition. In 2001, Zondervan was licensed the rights to publish this translation (the GNB 2nd edition) by UBS and, in cooperation with UBS, renamed it the Good News Translation (GNT).
So what is in PC Study Bible?
When listed as Today's English Version in the Navigation Panel, it is the first release of the entire Bible by UBS in this translation ((C) 1976). [This is referred to extensively in the UBS Handbook Series commentaries, which span the entire publication history of the translation. However, these commentaries do not differentiate between TEV/GNB/GNT; they refer to it simply as the TEV.]
When listed as Good News Translation in the Navigation Panel, it is the 2nd release of the TEV/GNB, which is now legally called the GNT ((C) 1992.
