What is the difference between city and county court?

My bf had to go to city court for damage to personal property (a drunken mistake). He was on probation for 6 months. Court was 7 months ago. Today he got a letter in the mail with a COUNTY court date for the same charge (the same occurrence...not to separate ones). What does this mean? If he already went to city court and paid the fines and was on probation, why would he now have to go to county court?