ss vs care
Information versus alert. "ss" says an enemy has disappeared; "care" tells a teammate to watch out. The first describes, the second orders.
ss
"ss" followed by a lane signals that the enemy on that lane is no longer visible. It is a fact, with no specific recipient: everyone draws their own conclusions. "mid ss" tells the two other lanes that the enemy mid may show up at their door.
open the page →care
"care" is an instruction addressed to someone: watch out, danger is coming. It is followed by the place or the threat: "care top", "care lvl 2", "care tf ult". It assumes you know what the threat is, not just that someone is missing.
open the page →Why they get mixed up
They get used together, "mid ss care bot", and that is where they blur. The difference is who it is for: "ss" talks about the enemy, "care" talks to the teammate. An "ss" without "care" is enough for an attentive player; a "care" without "ss" is an alert with no explanation. Both together is the complete call.