Are they? I thought that the Cabal are the Militant force ruling the galaxy, The Hive are the once trying to consume the universe in darkness, The Fallen Are a civization destroyed by the Hive, and The Vex are just Robots.
"Tactically efficient, disciplined, and unrelenting, the Cabal are the greatest known military force in the system. Their origins and ultimate objectives are a mystery, but it seems clear they have conquered more worlds than humanity has ever known.
Cabal soldiers wear pressurized armor that replicates the environment of their high-gravity homeworld. Their field tactics depend on ranks of Legionaries supported by air power, elite infantry, and ultra-heavy armor."
I also found something else out from a ghost fragments. Guardians die (like, permanently) if they stay away from the Traveler too long. This explains why you still "get consumed the the darkness" even though there is no hive (the darkness) around. Basically, your light gets extinguished.