Don’t worry so much about which. It is. If situational depression is unresolved, (that is, the patient cant bounce back from or change the situation)or very severe it is more likely to be called clinical depression. The same techniques of self care help for both and are absolutely necessary . Meds are not the magic bullet and will not help enough if you dont take care of yourself, try to resolve the situation or its impact on you. Of course the more moderate techniques are usually tried before medication, depending on the severity of the symptoms.
There is definitely overlap and having dealt with this for over 40 years and having it run in my family, I extremely object to non professional people saying you can easily differentiate between the two. I am getting very frustrated with people with no credentials thinking that some random article justifies broad generalizations.
The main point here is that you can help yourself by consulting professionals and taking steps listed in the article to take care of yourself.
I have a Masters in Library Science, so I do have a background in evaluating and applying the information in such articles.