it has not exactly like Juan describes. Depression is caused by things like loss of a friend or job, the death of someone close etc and normally people recover. CLINICAL depression is more severe is NOT caused by any of the things that can cause people to feel low and depressed. it is long-term or often re-occurring and lasts for many years or a lifetime requires CLINICAL help or Medical intervention that's why its called CLINICAL<-- from Medical

It depends on the context surrounding the sentence "I was in a depression./I was depressed." ("I was in depression." is not grammatically correct...) "I was in a depression." - OK, this is going to be remarkably petty, but 'depression' can mean a physical/geological one (that is a dip in the ground) (e.g. you accidentally drive into a rut, for a depression this is rather small scale) OK, seriously answering now, 'clinical', when appended to 'depression', typically denotes a professional diagnosis of one of the numerous forms of medically/psychiatrically recognised depression/depressive mood disorder, whether it is major/manic/chronic/atypical/melancholic/postpartum etc. etc. etc. (it could be a combination), whereas without 'clinical' there as a descriptor, it usually refers to a state of depressed mood, often acute. If the speaker is someone who is diagnosed as a depressive, then they both carry the same weight, though they would often not bother with the 'clinical' as to those who do suffer more severe forms of clinical depression, the word 'clinical' is in itself thoroughly unhelpful to them.

hi there, it depends on the seriousness of the depression. One can be intense and the other one mild.