Briefly, the sentence meaning approach to NLI takes the position that NLP systems should strive to model the aspects of a sentence's semantics which are closely derivable from the lexicon and which hold independently of context (Zaenen et al., 2005).
the speaker meaning approach to NLI takes the position that NLP systems should prioritize representation of the goaldirected meaning of a sentence within the context in which it was generated (Manning, 2006).