With AFB the larvae die after they are capped and usually after they start to pupate. With EFB the larvae die before they are capped while they are still larvae.
Bees uncapping white otherwise healthy looking larvae is normal. It is not a disease at all. They are removing them either because they are doing something hygenic and there was something starting to go wrong and they caught it, or they are clearing out brood because there is a dearth and they don't want more mouths to feed.
Here are pictures of brood diseases:http://www.kohala.net/bees/#anchor400987
Step through these and you'll see pictures of all sorts of brood diseases as well:http://maarec.cas.psu.edu/pest&disease/slide10.htm