There are three different Beowulf books published in the Norton Critical Edition series. The first, published in 1975 and edited by Joseph E. Tuso, is of the Donaldson translation. The second, published in 2002 and edited by Nicholas Howe, is also of the Donaldson translation. There was a third version, also published in 2002, and edited by Daniel Donoghue, of the Seamus Heaney verse translation which was originally published in hard-cover in 2000.
I have included images of the table of contents of each version so that you can see what other essays and, in the case of the third book, illustrations, are included in each book.
It is interesting to me that the first two books, which feature the translation by E. Talbot Donaldson, each have, on their spine, the name of the editor of the book (Tuso and Howe), while the third book, containing the Seamus Heaney translation, has the translator's name on the spine, rather than the editor's name. Someone at W. W. Norton has obviously decided that they need to cash in on Seamus Heaney's current notoriety.
I expect that most classrooms will either use the 2001 Seamus Heaney book (a paperback version of his 2000 book), which includes the Old English text, or they will use the 2002 Norton Critical Edition version of the Seamus Heaney translation, which does not contain the Old English text, but which does contain photographs of Anglo-Saxon artifacts and buildings, plus several essays.
There are many other translations of Beowulf still available in print, but the marketing people seem to be working overtime to convince everyone that the Seamus Heaney translation is the only one worth reading. I have written elsewhere on this website that I think that the Seamus Heaney translation is one of the best ones available, but it is a little unfortunate, I think, that many people will be greatly influenced by the marketing campaigns, and that they will not give serious consideration to any other translation.
In the Preface to his NCE/Heaney book, Harvard English professor Daniel Donoghue has, in my opinion, gone a little too far in praising the Heaney translation as being superior to all of the other translations which came before it. I would say that there are at least half a dozen other translations which are just as interesting as Seamus Heaney's version.
I will note as well that in his book, Professor Donoghue mentions that there is controversy over the dating of the composition of Beowulf, but he does not mention Professor Kevin S. Kiernan, or include any essays by Professor Kiernan in his book. He has included the J. R. R. Tolkien essay, written in 1936, which was a safe thing to do, I suppose, but which demonstrates to me that Daniel Donoghue is somewhat lacking in imagination (do we really need another printing of Beowulf: The Monsters and The Critics?). He has also included essays on Grendel's mother, and the Christian themes in Beowulf, which would seem to be directed at the hundreds of college professors and thousands of college students who choose "Women In Beowulf" and "Beowulf: Christian Or Pagan Myth?" as two of the most popular topics for their Beowulf essays. But he leaves out Kevin Kiernan, a man who has been described by the British Library as "the world's leading authority on the history of the Beowulf manuscript." Whether this was done for political reasons, or for other reasons, I have no idea.