"Mental illness" v. "Mental disorder".
Wikipedia seems to be taking the line that these two terms mean the same thing; and wikipedia at present seems to imply that the term "mental disorder" is preferable.
I think that the term "mental disorder" is preferable to the term "mental illness".
I don't however believe that they mean the same thing or infer the same thing.
"Mental illness" implies a biological illness; or if not a biological illness then a metaphorical illness.
"Mental disorder" of course means and infers disapproval of the behaviour that is supposedly "disordered".
The term implies that there is a mental problem of some kind and that there is a lack of organisation.
To say that someone's behaviour/thoughts/feelings are "disordered" is ultimately an opinion.
The term implies disapproval and not a great deal else.
Discuss.
However the term "mental disorder" is I think preferable to the term "mental illness" because it has at last set us free from the concept of illness being used in this sphere where it does not necessarily belong.