Originally Posted by HarryT
But, with respect, none of that affects the actual appearance of the book; it just makes it somewhat easier for the publisher to achieve a consistent appearance across a range of books. Please correct me if I'm wrong, but I don't believe there's anything in the way of formatting that a LIT book can have, but a MobiPocket book can't.
There's two issues: (1) actual capabilities and (2) practical use of capabilities.
For (1), there are a small set of formatting features Mobipocket does not seem to provide. For example, AFAIK there is no way in Mobipocket markup to specify a right margin (and only a right margin) for a block. More generally, LIT's HTML+CSS provides a richer vocabulary for expressing reflowable styles, allowing fixed, font-size-proportional, or page-width proportional units for all measures. Mobipocket provides only page-width proportional.
For (2), the two problems are conversion fidelity and rendering standardization. Most Mobipocket books probably begin life as some version of OEBPS markup+styles, then are converted to Mobipocket markup. If done incorrectly -- and from my experience the Mobipocket-provided tools are very much imperfect, not even really understanding CSS -- then the conversion loses formatting information. Even if done perfectly, correct rendering then depends on exact duplication of the Mobipocket rendering engine, which is not beholden to any external standard and details of which can change at any version.
So in general, (commercial) LIT e-books are better formatted with markup which is easier to re-convert and otherwise manipulate.