*i am not a professional* Mental health is something everyone has. Just the same as physical health, we all have both.
Mental illness is a when somebody is diagnosed with a disorder/condition which effects the way someone thinks/behaves in a serious way. These are illnesses like depression, OCD, all types or Eating Disorders, Biploar, Boarderline personality disorder- the list goes on.
Someone can be struggling mentally and not have a mental illness. It might make more sense if I explain it like this: mental health=your emotional well-being. So in other words being stressed/upset/overwhelmed/worried (or basically any emotion) is part or your mental health and when that emotion is negative it is effecting your mental welling-being which is why EVERYONE has mental health because EVERYONE has emotions. Therefore you can all struggle with that. The difference between struggling with your mental health and being mentally ill is something you can tell the different of by looking at the causes of someone feeling that way. For example someone could be feeling anxious because of they are starting a new job and they've never done it before. Or they are going on a date and they are worried about it or they have an assessment & they dont want to fail. The things they are feeling are rational, they have a logical reasoning behind them. When someone has a mental illness they will feel these emotions such as anxiety but the reason for it is irrational & illogical. For example they would feel extremely anxious about starting a new job but the reason isnt just the job and it doesn't make sense rationally. TRIGGER WARNING. The thought process COULD look like this 'im really scared to go to my new job - what if i do something wrong- That will make me a failure- Everyone will then hate me because I did it wrong and they might get angery at me- what if they shout at me- what if they fire me' - The thoughts can be different for everyone. Often to them it feels like the thoughts are GOING to happen. BOTH are equally important to raise awareness for. Just because you're not mentally ill doesn't mean your feelings are not important and that you dont need support.