What is the difference between obsession and addiction in psychology?

Addiction is a physical response in the brain, when the brain takes a substance, usually chemical, and uses it to become functional. It is also learning and a reward response.

So if you're addicted to running, you're really addicted to the endorphins released after exercise and your brain has adapted to that amount release, thus wanting more because it has to keep up with that amount. In order to attain more endorphins you have triggered the learning part of your brain when you go running. To make you continue the endorphin process in the future, your reward system is triggered when you run, so the next day you crave going for a run.

Obsession is also a learning process, but it more psychologically extreme. The other people's answers have probably already answered your question.

Obsession Psychology Definition

Obsession Definition Psychology

Obsession is being overly focused on one thing so that it prevents more important things from entering your life. Addiction is behavior that interrupts normal activity.

It is better to understand by example:

Obsession would be constantly worrying if you turned off the gas on the stove, addition would be returning to the stove again and again to turn it off.

One can equally be obsessed by worrying about their beauty, and an addiction to spending money on beauty products at the risk of not paying the bills.

In relationships, one could be obsessive about how they are viewed by their partner (or perspective partner) while additive would be to continue maintaining a relationship that is abusive.

obsession is wanting it but not nessacarly needing it.

psychological addiction is when you absoulutly cant live without it.

smoking is my obsesion i stop when i want but i like it so i do it.

addicted smokers go insane without it because it feels like your brain is going to bounce outa your head.

sorry i used smoking as an example