Everyone faces ordinary depression at some stage in their lives. If someone tells me ‘I’m depressed’, my answer would be ‘why?’ If there is a ‘good enough reason’ for a person to feel the way he is feeling, I’d call it ordinary depression. But if the reasons are not good enough, or there is no tangible reason at all for him to be in that state of mind, I’d think of it as clinical depression. It’s also possible that a person had ordinary depression but has suffered from it for so long that it’s become more serious. Genetic vulnerabilities, environment, how sensitive a person is .. all play a role.
Stress can be both good and bad. Some people work better under mild stress. You can call it effective tension. But obviously too much stress is neither good for your performance nor for your physical health.
Similarly anxiety can be as normal as stage fright, or in some cases it can become really debilitating.