How do I know if I'm sad or depressed?

depression and sadness can seem similar but they really aren't, sadness can only last up to a few days at max, depression on the other hand will linger and make you feel down all the time

When you feel distant, feeling like you have no purpose on this world, wanting to die or something..

You have difficulty falling asleep at night, you often feel tired and run-down, you often feel that life is not worth living, you sometimes feel out of control and lose all good judgement, you have trouble concentrating or remembering things, you think that sadness and disappointment are a regular part of life, and that "happy" people are only deceiving themselves, you have any chronic pain, headaches, etc. that are not due to a known illness.

If Its sadness, I will not be able to smile or laught, and if its depression, I'll hide my feeling behind my family face(just a mask of smile).

I diagnoses from a trained professional is the only way to know for sure, but there's a pretty good test on 7 cups :)

you can do a depression test on 7cups. It will help you to understand what you are feeling and it will make everything a bit easier. But when youre thinking about killing yourself, then youre obviously depressed.

Depression seems to be a state when 'hope' goes absent, when life feels disgusting for whole of 24hrs, when one feel like they can't have fun in anything anymore.

Being in the state of depression is much worse than being sad. Usually people get sad when it is raining outside, when their cat died or something like that. Depression is a medical condition that can be treated in many ways depending on the person's feelings, I guess. Sadness would go away very quickly, though depression is very much more painful and it takes time to make it go away.

يمكنني التغلب على كل المشاكل النفسية , بأستخدام التفكير المنطقي , وجعل الهدف في الحياة ليس العيش فقط , و إنما اكثر من ذلك ..

When you are depressed you are Feeling numb all the time. You don't care about anything anymore. I can stare at the wall for hours without moving once. When you are sad you have feelings, but only like sad/depressing ones.