Appearance and Nature. Edit
Where normal Titans start as all Silver Beings, their Aberrant siblings are all black with glowing eyes that often triangular but curved in appearance. Their hair is often spikes and while Titans grow features that are smooth, and sometimes even robotic, Aberrant Titans grow organic, and sometimes spiky armor. Sometimes their new features are...'organic' and chaotic in appearance and nature.
Their energy signatures are polar that of the Titans and they internally, have more in common with Eldritch Things. It is fair to called them Eldritch Ones in Titanoid/Humanoid/Titan form.
Back when the Titans used the Faceless Ones as a means of reproduction, many 'spawnings' were corrupted by Eldritch Powers, leading to the event called The Great Titan War.