Awoken:
It is said the Awoken were born in the Collapse, descended from those who tried to flee its wrath. Something happened to them out on the edge of the deep Black, and they were forever changed. Today many Awoken live in the Reef, aloof and mysterious, but others returned to Earth, where their descendants now fight for the City. Earthborn awoken sometimes venture out to the Reef, hoping to learn its secrets - but find no special welcome from the reclusive Queen.
Exo:
Exo began as self-aware war machines developed by humanity during the Golden Age for a long forgotten war, with the sole purpose of protecting their creators. They were rebooted during the collapse and now have no memory of their original function. Exos are "so advanced that nothing short of a Ghost can understand their inner functions. They remain ciphers, even to themselves; their origins and purpose lost to time. Whoever built the Exos fashioned them in humanity's image, gifting them with diversity of mind and body. Many of the City's Exo citizens live and work alongside their organic brethren, yet others fight again, reforged in the Light of the Traveler to serve as Guardians."
I don't trust 'em.