Can a Lacanian on here explain to me why the Real is sometimes defined as the failure of language (and thus not, strictly speaking, external to language) and other times defined as the outside of language?

I get that this kind of outside-in relationship is encapsulated by a word like extimacy, but i struggle to understand how this is distinct from a Derridean notion of there being no outside, period (which I don't take to mean that there are no "internal" outsides, so to speak)

I guess tbc my more relevant issue is how the idea of the Real as an outside to language (as something other than language) is held up as something Lacan has that Derrida lacks (oops), but elsewhere people don't seem to describe the Real as outside/other to language at all