Difference From Enablement
(A)    For enablement courts look at if patent is too broad. In general, courts only take extra-hard look at description when inventor has changed claims afterwards. Otherwise, court applies lower enablement standard. Not statutory, but this is how it works in caselaw.
(B)    WD: Arises in narrow subset – where you filed application than made changes to the claim that don’t seem to map perfectly to your specification. You can make changes to claim on your own volition, if changes move too far from original specification, then bar to new claim. You can change description while you work w/PTO, but only in small ways, specifications rarely change.