Quds is like CIA, but with more military muscle of it's own independent of irgc units... Members are selected not just for military skills, but language, looks, and ability to replicate and create forces quickly-such as the creation of Bosnian 5 th Corp in Bihac during Herzegovina war. Vevak is like FBI and when needed as brutal as CIA ,but is only internal. Artesh is large, powerful and formidable. Sepah is smaller, lighter and meant for fast deployment, quick penetration, enemy line disruption and asymmetrical warfare. Quds is not a superior special forces it's a covert, politico-military organization meant to perform different roles in different countries, but never inside Iran...and sorry can't give you a source