Todos can be written directly on the main screen. The memo pad opens a window. In addition, a new entry can be started just by writing in the Graffiti area in the built-in apps. Letters start a new description in the appointment book, numbers launch the time picker. Letters jump to that entry in the address book.
Letters start a new todo or a new memo in their respective apps.
Third-party apps vary in their paradigm. And sometimes the Jot area pops up when I don't need to do text entry. There has been a lot said about the difference in resolution on the two operating systems. On the surface the greater number of pixels would seem to be better, but in practice sometimes the Palm is more readable. In the default text size on the Pocket PC the font line is one pixel wide.