After describing for us the demonic horde which will some day arise out of the Bottomless Pit, in the Book of Revelation, the Apostle John then informs us that this infernal army is led by a Fallen Angel. His name in the Hebrew language is "Abaddon", which means "destruction". In the Greek language his name is "Apollyon", which means "destroyer". Thus we see that they are in effect synonymous terms. Consider the following verse:
"And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon."
Revelation 9:11, KJV
For additional information concerning this topic, please refer to such articles as "2012 - New Age Deception and Psychobabble