Is there a difference between "classification" and "labeling"?
Totally disagree with @Derek Janni. Be careful about notation however you should not get lost in terminology. Those papers you mentioned used the term "labeling" literally but in Machine Learning/Data Mining community, labeling is the process of preparing data for supervised learning (classification)! It has nothing to do with the ML task!

Those papers used the term to show that after supervised learning they can recognize different labels of different objects so they used the term labeling but you probably can not find in any literature that they use these two terms as synonyms.