I'm having a hard time telling the functional difference between ldifde.exe and csvde.exe. The Microsoft curriculum feels unhelpful to me on distinguishing between situations where one should be used over the other. Does ldifde just supersede csvde? The TechNet pages imply that ldifde's functionality is a superset of csvde's.
CSVDE can be used to export and import (add) object data only, LDIFDE can be used to modify and delete AD objects and supports populating passwords which CSVDE doesn't (amongst other things).
LDIFDE is not really a superset of CSVDE, it's a different approach with a lot more power and complexity. CSVDE is handy because it is generally much easier to manipulate the raw CSV format data but it is a lot more limited. If all you want to do is add a bunch of users into an OU then CSVDE will do the trick but if you want to modify a bunch of properties for collection of objects then LDIFDE is the way to go.