Jargon is the specialised vocabulary of a particular profession or field, and it is used because it is precise, even when it leaves outsiders baffled. Slang is very informal language that people use casually, and it exists more for colour and identity than for technical precision. A handy way to remember the split: jargon is what a job needs, slang is what a group enjoys.
The core difference
Jargon is technical, profession-specific vocabulary, while slang is informal, casual language not used in standard speech or writing.
- jargon — specialised vocabulary used by people in a particular profession or field, often hard for outsiders to follow: The contract was full of legal jargon that confused the client.
- slang — very informal words and phrases not used in standard, formal speech or writing: Teenagers invent new slang faster than dictionaries can keep up.
- slang — also the specialised vocabulary of a particular group or profession: Doctors use their own slang that can baffle patients.
How to tell them apart
The two overlap more than people expect, since slang can also refer to a group's own specialised vocabulary, much like jargon does. The clearest difference is tone and purpose: jargon exists to be precise and efficient within a profession, even if it sounds dense to everyone else, while slang exists to sound casual, playful, or informal, and it would feel out of place in a formal document.
Legal jargon and doctors' slang both baffle outsiders, but only one of them would show up in a contract. If the vocabulary is meant to be exact and professional, call it jargon; if it is meant to be relaxed and everyday, even within a profession, slang fits better.
