Spent 20 years in the intel business before returning to higher ed eight years ago.
Sounds like you got a somewhat misleading definition from your SSO.
Levels of classification reflect the sensitivity of the material and the damage it would cause to national security if that information was revealed. In that sense, there is a discernible difference between the disclosure of “confidential” data, versus something classified at the Top Secret/SCI level.
Your clearance (and need to know) determines your access to the vast majority of classified information. The amount of material covered by Special Access Programs (SAP) remains relatively small, by definition. If most classified was covered by various SAPs, the mechanics of reading people into the program and debriefing them would be a massive headache, to say the least.
That’s why SAPs are typically reserved for our most sensitive collection efforts—known by a relatively small number of people, and with the material/databases segregated from the vast “haul” of intel information. Many SAPs are actually “housed” in a separate vault, inside a Sensitive Compartmented Intelligence Facility (SCIF).
All that also used to depend on who you are working for. Things certainly changed under Clinton - got worse if you ask me.