"Il s'agit de..." vs "C'est..." ?

Question

Having asked this question previously, I do know what s'agir means, somewhat. However, it seems to me that I most often see it used in a way that in English would translate directly to "It's..."

This leads me to be uncertain as to how it differs from simply using C'est...

For instance, what is the difference between the following two sentences?

Il s'agit d'une pièce à deux personnages.

C'est une pièce à deux personnages.

I would think both mean "It's a play with two people."

Likewise, here are two more:

Il s'agissait en effet de Drago Malefoy.

C'était en effet Drago Malefoy.

How do these differ? Are there certain contexts where Il s'agit de... is simply more appropriate, like when describing the content of something, what it consists of?

Answer 1

The examples you gave are all the same in that they give the same meaning to s'agir. But this meaning changes depending on the context.

I'll give you few examples without trying to be exhaustive:

• Non, il s'agit de faire l'évaluation complète de la situation avant de prendre une decision quelconque! ⇔ No, we have to/must perform a thorough assessment of the situation before taking any decision!
• Dans le corps humain, quand la cellule a besoin de se diviser elle reçoit un signal qui lui donne la permission de se diviser ou l'obligation de déclencher le processus de l'apoptose. L'apoptose est le processus de suicide cellulaire programmé. S'agissant du cancer, c'est justement le refus ou l'échec de la cellule à répondre au devoir de se suicider ⇔ In the human body, when a cell needs to divide, it receives a signal to either divide or trigger the apoptosis process. Apoptosis is the process by which a cell suicides. Concerning cancer, it's the fail or refusal of the cell to trigger the apoptotic process.
• Il s'agit d'un test à trois étapes: collecte d'information, analyse des vulnérabilités et l'exploitation de celles-ci. ⇔ It consists of a three-step test: information gathering, vulnerability analysis and their exploit.
• Il s'agit avant tout d'être juste avec toi-même. ⇔ Above all, it's a matter of being fair with yourself.

Answer 2

I think that Il s'agit is inviting you to imagine something, to imagine something which I am imagining ... something I am describing which is not evident.

• If I'm selling you a house you haven't seen, and I want you to imagine it, if I want you to give life to it, to animate it in your mind as I describe it, "Il s'agit d'une pièce principale bien orientée...

• If I'm telling you a story, "Il s'agissait..."

• If I'm telling you something plain and obvious, right in front of us, "C'est un chat."

There might be a hint of how to use it in the "Ce" which can mean "this" ("Ceci n'est pas une pipe") ... "Ce" and "C'est" are more for things which are "this", i.e. for things which are here and now.