What are the DoD's two broad categories of information?

The U.S. classification system is currently established under Executive Order 13292 and has three levels of classification - Confidential, Secret, and Top Secret. There is a designation of "unclassified" but by definition that means it is not "classified".

Other markings may be added to these categories. Subsets of these classifications may include: Controlled Unclassified Information (CUI) - sometimes also referred to as FOUO (for official use only) or Sensitive but Unclassified (SBU) - although use of the term SBU is supposed to be discontinued, Secret No-foreign, Secret with restrictions to certain countries, Secret-Compartmentalized, Top-Secret Special Compartmentalized Information (most TS is also SCI), Sources and Methods Intelligence (SAMI), ATOMAL (for atomic energy).