Sinon and autrement are apparently identical in being able to express three meanings: gradability, logical alternatives and topic change. It is shown that these two connectives do not express the three meanings in the same way, however. Autrement always implies a discourse frame within which the connective indicates an exception, which explains why autrement has more to do with homogeneity than with gradability and shows affinity with positive polarity. Sinon establishes a new assessment of a previous utterance, and in so doing marks a sharp discontinuity from it. As it is not lexically linked to that utterance, sinon can be semantically ambiguous, introducing elaborative or antithetical sequences, often non-predictive and moving easily from language to metalanguage. Of the two connectives, sinon is the only truly alternative one: c’est un mâle (sinon/*autrement) une femelle.