Looks like it is rendered to a page size that is intended to fit nicely on the device's screen at the default zoom/dpi settings without significant borders and have the text at a comfortably readable size. Look at the print preview in Adobe's reader with page scaling turned off and you'll see the difference. The other editions I've looked at would print nicely at A4 size, if this was printed like that the text would probably seem too large.

Different dimension and larger font (the entire layout changed as well because of those). The usual PDF is optimized for print.