We jacked the terms from linguistics; they're actually truncated forms created from "phonetic" and "phonemic." An etic framework is one designed to be generalized or universal, whereas an emic one is specific to a particular set of data. In folklore, for example, one can talk about etic categories of "myth," "folktale," "legend," and so on, or emic categories drawn from the culture in question, which might be things like "winter tales," "hot speech," and so on. Both angles of analysis are useful, especially when you can lay them against one another to see what intersections or patterns emerge.