How to respond to a two very different referee reports?
Follow carefully the indications of the editors, and to the best of your ability try to follow the ones by the referees. Usually both agree and so there is no conflict. When there is, then the editor's opinion wins, as they are the ones with the power to decide whether your manuscript will be accepted or not. That being said, it is wise to not ignore the comments from the referees even if they seem to have been ignored by the editors. If the referee claims your work does not add anything new to the field, what would you answer? I would try to see it as a valid criticism and answer it the best I could. Think that this kind of question can come also in e.g. a conference! In that context what would you answer?