Neither one is a death sentence, and neither one has a magic cure. EFB and chalkbrood show up when a colony is stressed. Here is how to tell them apart from each other (and from AFB), and how to remove the stress.
American Foulbrood: Signs, the Ropiness Test, and What to Do (Including the New Vaccine)
Sunken greasy cappings, a foul smell, and larvae that rope out an inch on a matchstick. American foulbrood is the one disease you cannot manage your way out of. How to confirm it, what the law says, and what the new vaccine does and doesn't do.