In short, there is a difference. 1/8" difference on 232 pages in this example, which makes an assumption that the ASM vol 5 MW uses paper similar in thickness to an Omni. I doubt they're the same, but as an example, on 1/8" for 232 pages - bump that up to a 700 page book, and that's 3/8". A handful of Omnibus later, and that's an extra Omnibus you can fit on a shelf!