As nouns the difference between expense and choragus
is that
expense is a spending or consuming often specifically an act of disbursing or spending funds while
choragus is (historical|ancient greece) a chorus leader, especially one who provided at his own expense and under his own supervision one of the choruses for the musical contests at athens.
As a verb expense
is to charge a cost against an expense account; to bill something to the company for which one works.