Um…wasn’t Truman Capote’s book, In Cold Blood?
You are entirely correct. I was busy coughing and got it wrong. I blame the Etruscans.
Novels, by nature, have a cohesive narrative. Books don’t have to. Narratives make novels.
Since novels are sometimes published serially in magazines or newspapers, “subset” isn’t quite right either. The set “book” almost includes the entire smaller set of “novel.”
Wait, is In Cold Blood classified as a “novel”? (Is that the point being made upthread?) I’ve never thought of it that way, myself.
Okay, here’s a question: if a novella is shorter than a short novel, what’s longer than a long novel?
Capote (and then Mailer, and countless others, no doubt) referred to what he was writing as “a non-fiction novel,” which is a sort of contradiction in terms, but he was looking to be released from the journalistic stricture of recording dialogue accurately, from describing things he hadn’t actually witnessed and taken notes on, etc. He used novelistic techniques, in other words, to do the job that journalism usually covered.
A novel is a single work of narrative fiction, above a certain length, presented in prose form.
A book could be a novel, a novella, a novelette, a short story (which would make for a short book, but, hey), visual material, a poem, a script, non-fictional material (didactic, journalistic, philosophical, etc), a collection of some combination of the above, or even a part of one of the above. It may lack narrative, even if it’s a single cohesive and complete work.
A novel isn’t necessarily a book, any more than a book is necessarily a novel - they can be serialized, they can be collected with other works, they can be broken up into multiple volumes.
Hell, I’d argue that a novel doesn’t even necessarily have to be written. If I listen to the Books-on-Tape version of Lord of the Rings, I’ve just heard a novel. But not, ironically, a book.
Tolkien wrote The Lord of the Rings as one novel split up into six sections (plus some appendices). He called those six sections “books.” He never intended The Lord of the Rings to be published as six volumes (or maybe seven, counting the appendices). He intended it to be published in one volume. A “book” was merely Tolkien’s name for a section of the novel. His original publisher looked at how long it was and said, “This has to be published as three volumes.”
Grab your copy of The Lord of the Rings. Notice that it’s split up into six books, two for each of the volumes, and each book is split up into chapters:
The Fellowship of the Ring (Books I, The Ring Sets Out, and II, The Ring Goes South)
The Two Towers (Books III, The Treason of Isengard, and IV, The Ring Goes East)
The Return of the King (Books V, The War of the Ring, and VI, The End of the Third Age, plus the appendices)
This is the division that the publisher insisted on. Many later editions are one-volume editions.
There are seven-volume editions as well, like this one from Harper Collins. Some people prefer these for essentially logistical reasons. The one-volume tomes can be physically and mentally daunting; some built-in intermissions are nice.
The last time I looked at such an edition in person–not this one–there was a sticker on the wrapping that said it was Tolkien’s preferred presentation.
Right. “True Blood” was obviouly a Type O. 
I knew that there was at least one case where The Lord of the Rings was split up into seven volumes. It was a limited edition boxed hardcover, and the number of copies published was rather small. I believe that there’s no evidence that Tolkien wanted The Lord of the Rings to be published in seven volumes. The publisher was merely making things up for that sticker, I’m pretty sure. Tolkien wanted the novel to be published as a single volume.
In fact, if you want to be technical about it, the traditional idea of a novel is a narrative about how one central character develops and changes internally over the course of a certain period of time. So something like The Odyssey wouldn’t be a novel (in the technical sense) even if it hadn’t been written in verse, because it doesn’t really revolve around the workings of Odysseus’ inner psychology. When the Odyssey was created, the novel as a from of writing hadn’t been “invented” yet.
You might apply this standard to the LotR and see that it’s not technically a novel either.