A very graphical convention encountered time and again in the manga adaptations is the complete absence of backgrounds when a dramatic moment demands all attention to the foreground. When Obi-Wan sacrifices himself to Vader's blade, the moment takes place against stark white, so as to leave little doubt as to what happened.
The American version has to have the action of Kenobi's disappearance occur in only two panels, so it makes the most of it by having an extremely dramatic frame of Vader's strike, followed by Roy Thomas' descriptive text further detailing what has just occurred.
