So you thought depression was just depression, well as time has passed there are sub categories on top of categories.
Atypical and melancholic depression each have there own unique classifications, but all depressive illnesses have the same basic undertones.
Read more to find out the unique features of the two mentioned.
You could almost make a case that one can get more depressed trying to figure out what type of depression they have as we get more classifications coming out from the medical system.
If it helps get to the root cause and you find a cure then were all for it.
Lets look at some of the symptoms that characterize these two types of depression

1. Melancholic - is basically a loss of pleasure in something you normally like.
   The sign that you have this type of depression is normally good news that would cheer you up doesn't anymore.
     Subjects that stimulated you before don't anymore and nothing seems to help.
   
2. Atypical - is more of a "Moody" type of depression.
   Events can drive you quickly into a deep depression or if good things happen you can quickly change gears.
   The end result is still a emotional ride which is outside the normal ranges.
   

These two types of depression still have some common symptoms like energy drain, weight gain or loss, sleep disruption and a few others.
The problem with these types of depression is by the time you discover what you have there could be severe damage.
The damage we talk about could be due to prolonged use of drugs, health issues and the deep roots of mental drain that depression breeds.
Depression is not your friend, it tries to be faceless but eventually rears it's ugly face as it tortures you.