Dialect
Part of speech: noun
Definition: A variety of a language (specifically, often a spoken variety) that is characteristic of a particular area, community or group, often with relatively minor differences in vocabulary, style, spelling and pronunciation.
Example sentence: As someone who's been doing a lot of classical theater recently, I loved the idea of getting to run around in Steven Alan, and not be in a corset and a wig, and not have a dialect, and get to be in a 90-minute play with no intermission, and get to do real comedy.
Idiom
Part of speech: noun
Definition: A manner of speaking, a way of expressing oneself.An artistic style (for example, in art, architecture, or music); an instance of such a style.A locution peculiar of a particular language, that cannot be understood by way of a literal translation.A communicative system under study, which could be called either a dialect or a language, when its status as a language or dialect is irrelevant.A programming technique which experienced programmers in a language are assumed to know.