The Tractatus is a product of what is called the early or first Wittgenstein, while "On Certainty" belongs to his latter stage. By that time he had repudiated the emphasis of the Tractatus on logical correspondence with facts and switched to speaking of language games and practical uses. In both phases his position on "unspeakable" things like ethics and metaphysics was similar (roughly the one Danfly summarizes at the beginning of the parent quote).