Display: E7 is a 4" panel with a 640x360 res while 800 is a 3.7" panel with 800x480 res however E7 is pure RGB compared to the pentile on the 800 (you choose who wins; although if you ask me my n9 display is something I like more so the 800 is IMO nicer to look at)
Keyboard: E7 has a hardware keyboard after all Size+Weight: related to your keyboard preference