A habit is something you do regularly, often on autopilot, while an addiction is a compulsion that keeps going even when it is causing harm. Checking your phone every morning is a habit; needing alcohol despite it costing you your job is an addiction.
The core difference
A habit is routine behaviour; an addiction is a harmful compulsion that persists despite the damage it does.
- habit — something done regularly, often without thinking: She is trying to build a habit of reading before bed.
- addiction — a harmful compulsion to keep using a substance or behaviour, even when it causes problems: His addiction to alcohol cost him his job.
How to tell them apart
The clearest test is harm and control. A habit, like checking your phone first thing every morning, is simply routine, and most people could change it with a bit of effort. An addiction is different: it keeps going even when it is visibly causing problems, whether that is a job, money, or health, because the compulsion overrides the person's ability to just stop.
The words do overlap at the edges. Habit can also describe a hard-to-break dependency, as in a smoking habit, which is why people sometimes use habit as a softer, less alarming way to describe what is really an addiction.
