SEBoK vs. INCOSE SE handbook is a bit of a mystery to many. Meaning that I get asked the questions what is the difference between the two and which one is better?
There are quite a few twists and turns to this so allow me to be concise and direct.
In terms of details SEBoK is just under 1200 pages while the current handbook is about 300 pages. Also the former is 'part and knowledge-area driven' while the latter is organised in chapters. SEBoK is also wiki-based and roughly updated roughly every 6 months. The current version, as I write, is 2.7 (a copy is 'pinned' for you to the right for convenience). You can download it free of charge either all-in-one go or the parts of interest to you: Download SEBoK PDF - SEBoK (sebokwiki.org). SEBoK is also run by multiple organizations including INCOSE, I'll let you discover the others by going to the website.
The handbook i.e., V4.0 is exclusively the text to be used to prepare the SEP exam. I personally use it as a day-to-day reference, for my SE training including SEP exams preparation and also SE promotion in general. The handbook costs around 70 euros and is available through the Wiley, Amazon etc. If you are an INCOSE member the handbook is free and downloadable. The best way to appreciate the handbook is to apply it! In terms of content there is more to it than meets the eye so don't think that the contents are 'chiseled in stone', that's why application is fundamental to understand the reasoning behind it.