Up until I started reading through Russian Review Grammar by Marianna Bogojavlensky I had only seen ничего offered as a translation for the English "nothing." Bogojavlensky's text, however, often uses нечего in its example dialogues as in the following sentence:
Если это так, то я могу чувствовать только жалость к тебе, и мне нечего больше прибавить к тому, что я сказал.
Here is the translation the text offers of this sentence: 'If this is so, I can feel only pity for you, and I have nothing to add to what I have said.'
Is the use of нечего in this sentence just a simpler way of saying "у меня нет ничего больше прибавить... ?" One thread I looked at on Word Reference said that ничего stresses a kind of "absolute negative" while нечего merely stresses absence. Can this distinction explain the example given above? Yandex's dictionary defines нечего as 'there is nothing to + inf' or as 'it's no good to + inf.' While I can understand how these definitions differentiate the usage of нечего from the usage of ничего I don't see how this makes "и мне нечего больше прибавить..." preferable to "у меня нет ничего больше прибавить... ?