UBlueprint
The UBlueprint object is the actual Blueprint asset you have in the editor.
This means that there is one UBlueprint instance for each Blueprint asset.
Warning
UBlueprintis an editor only concept
You can get the UBlueprint from an UClass by using ClassGeneratedBy.
UBlueprintGeneratedClass
Objects ending with _C are UBlueprintGeneratedClasss
You can see it as the cooked blueprint class (the thing that is being created when you press the BP compile button next to the save one).
You can get it by casting an UClass to an UBlueprintGeneratedClass