Slang and jargon are both informal vocabularies, but differ in their usage. Slang refers to informal words used in certain social contexts, while jargon consists of specialized terminology used within a particular field or profession. Jargon aims to precisely define terms for practitioners of a discipline, whereas slang is more casual and seeks to identify social groups through novel word usages. Both can evolve over time, with some slang terms becoming standard language and jargon spreading more widely as fields grow in popularity.