I feel that depression is a constant unhappiness that stays firm in someone's heart, and more often than not accumulates over a period of time.
Loneliness is specifically the result of experiencing, or feeling, no friends or people that care for you, whether there are people or not, which is a form of mild depression.
Heartbreaks can occur either when an extremely high accumulation of depression finally bursts out of control, or when a sudden tragic event occurs with a powerful blow to the heart.
Being different from peers can be defined as any significant difference between him/her and the general features of the people around. Such differences may be physical defects or disabilities, which dramatically affect the mobility, senses and appearance of the person, or mental problems, which makes the person look inferior, lacking the average sane and sound mind, or simply an unusually special personality, including special personal interests or eccentric daily-life habits.
Having to put up a front means that the person is undergoing some state of depression, but does not wish to exhibit his/her emotions to the people around him/her and thus deceives people by behaving as if all is well and normal. This prevents people from detecting the trouble or problems he/she is currently facing. However, this cannot continue long before experiencing a heartbreak.
Up to now, I have not experienced any type of depression, which only allows me to give suggestions as to how depressions can be dealt with. I would tackle the depression, whatever it may be, head on, as depressions, having such a stubborn and destructive nature, linger in one's soul like a leech attaches itself to a dog. I would question within my heart what really is the problem, going down to the roots of the weed, rather than to the obstinate leaves. Once the problem is located, it can be done away with easily. It must be questioned whether this depression is merely a act of self-pity. For that case, the person must rid himself/herself of his/her pride.
In the matter of loneliness, it is a truth that I feel somewhat disconnected from other people. I am the sort that tends to keep to myself, this causing an unwanted hindrance to making friends. Of course, the obvious solution to this is very simply to be more confident and less reserved to one's self, though this requires certain courage and effort to achieve. That is my situation. However, if the people around the person continuously and relentlessly display a negative attitude towards him/her, he/she will have to consult an understanding adult, his/her parents or teachers, or anyone who he/she can confide his/her troubles in.
As for heartbreaks, I have not experienced any, and certainly desire not to experience any in the future. In this case, the person, in his/her state of deep sorrow and grief, temporarily rendered helpless to comforting himself/herself, requires someone to comfort him/her, and continue to support him/her until he/she makes a complete psychological recovery.
For being different from peers, this is all up the decision of the person. I fall in the 3rd category which I had made, on the shallowest, mildest level. The thing about me is that I am fascinated in a topic in which nearly all the people I meet everyday do not take an interest in. Understandably, everyone has unique traits. But I feel exceptionally different as others have a greater overlapping of interests, and they thus find it much easier to converse with each other. I, lacking this overlapping, have a greater difficulty in making friends, especially with my habit of keeping to myself. For others who have physical or mental defects or differences, have no choice but to overcome these problem as they are permanent and cannot be taken away from them.
I have not put up a front and seriously discourage it. You are literally denying yourself the chance of letting other people know of your plight and come to your emotional rescue. For those who put up a front, I propose that he/she would stop immediately and get help from someone.
This is my perception of these emotional troubles and how one should deal with them.