Essa é uma questão lingüística, não matemática.

Em português há uma diferença diminuta de sentido entre "diferenciável" e "derivável" (na Análise Matemática mesmo), mas não recordo mais qual.

O inglês sendo o idioma mutante que é, talvez acabe absorvendo essa diferença de nomenclaturas dessa forma: derivable x differentiable.

I understand that it is simply a difference of language and that the intent is the same, but in mathematics precision of language is incredibly important. This is a common error in English.

I just want to reflect on the irony of your having no trouble replying to a comment in Portuguese about how it's important to use the right term. This whole thing has brightened my day.

Translation:

That's a linguistic question, not a mathematics one.

In Portuguese there's a very small difference between "differentiable" and "derivable" (in the context of Math Analysis), but I don't recall it.

English being a mutable language, may end up absorbing the difference between nomenclatures in that way (??): derivable x differentiable.

Sorry French guy here. Wrong translation . Thanks for pointing out