What makes the IRGC a terrorist organization but not the FSB?

The Islamic Revolutionary Guard Corps (IRGC; Persian: سپاه پاسداران انقلاب اسلامی, romanized: Sepâh-e Pâsdârân-e Enghelâb-e Eslâmi, lit. 'Army of Guardians of the Islamic Revolution' or Sepâh for short) is a branch of the Iranian Armed Forces, founded after the Iranian Revolution on 22 April 1979 by order of Ayatollah Ruhollah Khomeini.

The IRGC is designated as a terrorist organization by the governments of Bahrain, Saudi Arabia and the United States.

https://en.wikipedia.org/wiki/Islamic_Revolutionary_Guard_Corps

Not against the IRGC being listed, but what went into that and how is that going into a decision for NOT including the FSB AKA the Federal Security Service of Russia for being under that same designation?

-Despite the 1999 Apartment Bombings?
-Despite the poisoning of Alexander Litvinenko?
-Despite the assassination of Anna Politkovskaya?
-Despite the 2014 Vrbetice ammunition warehouses explosions?
-Despite the poisoning of Sergei Skripal and his daughter?
-Despite the poisoning of Alexei Navalny?
-Despite the actions they made in the war on Ukraine?
-Despite the assassination of Darya Dugina?
-Despite the amount of control the FSB has over Russian lives?

Mirrored at the Nerve Center as "terrorist organization"

Categories: Class disparities, Double standards, NOT, Selective outrage, Serious consequences