What's the difference between a Singleton set and its member?

Let $S$ be a set, then ${S}$ is also a set, namely the set that contains the set $S$.

Barack Obama is an individual person, while ${text{Barack Obama}}$ is an abstract object that may not have nothing more in common with the individual himself other than that it contains Barack Obama inside it, and they both cannot be the president of the United States since Barack has served two terms.

They are dissimilar in the sense that ${text{Barack Obama}} subseteq {x: x text{ was or is President of the United States}}$ while the individual Barack Obama does not share this property with ${text{Barack Obama}}$.

• $a$ is an element of the set ${a}$.
• ${a}$ is a set that contains an element $a$.
• $a$ and ${a}$ are two different objects.