The Potara Earrings are earrings that give the 2 users the ability to fuse with each other.
a Earrings are the earrings that Supreme Kai's wear for casual wear. They were introduced during the Majin Buu Saga and are in Dragon Ball Z. The Potara Earrings have created Old Kai, Kibito Kai, and Vegito. But the only set back of the Potara Earrings are that the fusion is permanent unless the fusion is done by two Non-Supreme Kais.
Unless they're in an area that cannot support them, like Super Buu's stomach. Whichever fusee is stronger is in control of the Fusion. For example Kibito Kai and Old Kai. Both fusee's that are Supreme Kai's are in control of the fusions.
Old Kai= Old witch and Supreme Kai (old one)
Kibito Kai= The Eastern Supreme Kai and Kibito, his Bodyguard