The full name of SAD is special activity division, that is, special operations department. As can be seen from the name, this is a very illusory unit. In fact, SAD is nominally affiliated with the State Secret Service of the CIA, which is also a very empty name. But SAD is not a specific "special force" or "action team", but a very abstract organization.

SAD is basically divided into two parts, one is responsible for the so-called tactical paramilitary actions, that is, paramilitary tactical actions, and the other is the so-called "special forces", which are responsible for rescuing, secretly killing, infiltrating, destroying and training military personnel. The other part is responsible for covert political actions, that is, secret political actions, including many "black actions" that we often see in movies, TV dramas or novels, such as subversion, psychological warfare, economic manipulation, elections and so on.

Therefore, SAD is the core and key of CIA espionage, and the public content is very abstract and unrealistic. The existing materials are either publicly released official materials or pieced together from various news reports, and some of them are simply speculation and fabrication.

Sade's agents are what we call "spies" and "secret agents". Indeed, most of them are selected from the army, and the source is naturally elite troops such as seals and deltas. The actions of SAD members are naturally top secret, and the specific details cannot be known to outsiders unless someone breaks the news. For example, the popular movie "The Assassination of Bin Laden" and the novel "A Hard Day" written by an anonymous Navy SEAL describe the story of the action led by CIA agents to eradicate Bin Laden. These CIA agents, who are responsible for collecting intelligence and directing special forces to carry out surprise operations, are heartbroken, but in fact, it was the SEALs who really shot and killed bin Laden. In other words, the members of SAD are not all soldiers who carry out assassinations with guns. SAD can mobilize special forces through SOCOM when performing tasks, or it can be darker and hire third-party personnel (such as military contractors and even killers).

This also answers your question. In fact, SAD is completely different from delta seal. Delta and seal are just guns, and SAD is the real gunman. You can even understand SOCOM as a gunman, while SAD and CIA are more like commanders who command gunmen to fight.