Twitter CEO Dick Costolo, fresh from a day of smartphone Twitter app releases, said Tuesday night that his company saw Apple as a “mentor” to Twitter.

“Apple is in many ways a mentor company for us,” Costolo told PBS interviewer Charlie Rose. He said the companies had “a great relationship.” Facebook, by contrast, got this chilly description: “We’re very different companies.”

Facebook was pursuing symmetric networks, Costolo said, but Twitter saw the world as asymmetric. They were fundamentally opposed, and competed for ad dollars.