Jess,
I am not a linguist, and my answer will probably not satisfy you. I do know that I have asked a similar question about the "tones" of Toner Analyzer, and the "tones" of Natural Language Understanding (NLU). The tone algorithms and models used by the two services are different. Neither one is wrong, they were just trained differently, and have different underlying machine learning models.
What I usually tell customers who are looking for tone data is to try both. See what the cost differences are between the two of them, and see which model better fits the needs of your particular use case.
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Daniel Toczala
Community Leader and Customer Success Manager - Watson
dtoczala@us.ibm.com------------------------------