If the 'hook' is solely aimed at an agent or a publisher, I would agree, Danny. But as I understand it (and I'm open to correction from those more experienced then me) the elevator pitch should try and summarise all of your story; everything that an agent or publisher will need to know to ensure you have a 'complete' narrative. The hook, on the other hand, is aimed at a wider audience which includes your potential readers, and there may be things that you want to withold from them so that you can spring a surprise on them at the relevant point in the story.
So, for instance, the elevator pitch that I eventually arrived after Harry's interesting webinar and the ensuing blog post a while ago, is:
When an ancient device is uncovered with the power to recreate the world anew without flaws or imperfections, a limbless thief must decide whether to sacrifice who she is now for the chance to reclaim who she once was.
That's a pretty good summation of the entirety of both the external plot and the protagonist's inner conflict. The first few words give away exactly what the nature of my 'McGuffin' is, something that the protagonist (and therefore the reader) don't find out until more than halfway through the story. Also clearly stated is the choice that the protagonist faces at the climax of the book which will resolve her inner journey.
An agent or a publisher might need to know both those things before deciding whether it's worth their effort to read on. But I wouldn't want a potential reader of the book to know about either of them before they start to read.
So my 'hook' - if aimed at the wider readership - has to be different and more limited than the pitch. It has to entice and tantalise the reader without giving away those aspects of the plot or theme that I want to keep in reserve.
How the hook is delivered will vary. It can be the first sentence or paragraph, a well-chosen tag-line, the back cover blurb, a 'high concept', a particularly unusual character or setting... or a combination of any or all of these.
It's anything that makes the reader want to read on... or buy the book.
Anyway, that's how I currently understand it. The fact that there's so much discussion and debate, though, reveals that it's not at all cut and dried. So others may have a different take. 😆