My recollection is the CIA considers any military aged males in the area of a strike to be enemy combatants, which could be one cause for significantly different numbers.
"It is also because Mr. Obama embraced a disputed method for counting civilian casualties that did little to box him in. It in effect counts all military-age males in a strike zone as combatants, according to several administration officials, unless there is explicit intelligence posthumously proving them innocent."
Here we go:
http://www.nytimes.com/2012/05/29/world/obamas-leadership-in...
"It is also because Mr. Obama embraced a disputed method for counting civilian casualties that did little to box him in. It in effect counts all military-age males in a strike zone as combatants, according to several administration officials, unless there is explicit intelligence posthumously proving them innocent."