Whats the difference between personality disorder and mentall illness?

A personality disorder is a type of mental illness. There are a range of mental illnesses e.g. depression, schizophrenia, anxiety disorders, anorexia nervosa. They can be either inherited or learnt. You could ask her to go to the Doctor's with you to see if she has a disorder. If she does, he could prescribe her drugs (e.g. antidepressants) or refer her to see a counsellor. You should perhaps encourage your daughter to go to college or join some groups e.g. the gym. Tell her the consequences of lazing around all day e.g. she'll end up with a job she doesn't like. Tell the consequences of having unprotected (whether she is or isn't) e.g. that she could get STIs and STDs. But since your daughter is 16, there's not a lot you can do, except for threatening to kick her out of your house if she doesn't pull her socks up. But I wouldn't suggest this, because she could go back to her father or move in with a boyfriend. Then she would be even further from you, and you wouldn't be able to keep an eye on her at all. Good luck! :)