Zeus is the yellow bird on the top of the cage.  She is a Lutino cockatiel.  This coloration is only found in captivity. Lilly is hanging out with her.  He's the Grey to her left.

Yoshi’s on the left (Male pied cockatiel). Lilly’s on the right (Male grey cockatiel.  This is the coloration found in the wilds of Australia).

Lilly in my fake tree.

Lilly on the left.  Zeus on the right