They agree.  They just measure different things.  918 is the total dead.  Here are the hard breakdowns by locale: 
 *909 - died in Jonestown itself (Pavilion, walkways, West House, etc.).  This includes two gunshot wounds (Annie Moore and Jim Jones).   
 *4 - died in Georgetown at Jones' command.  Sharon Amos killed her two youngest children, then helped kill herself, then Liane killed herself.  All with a knife. 
 *5 - were first shot two hours or so before at the nearby airstrip, with their deaths used as the pretext for the rest having to commit suicide.  Note, confusingly, Patty Parks was a PT member who had just defected, so different media sources count her still among the "cult members" dead. 

 Published combination numbers in the media 
 *907 - 909 - 2 = 907 died of poisoning in Jonestown (though Annie also ingested poison) 
 *908 - "Victims" in Jonestown sometimes  some exclude Jim as a victim (909-1 = 908) 
 *912 - "Victim" PT members, including the 4 in Georgetown (908+4=912) 
 *913 - PT members dead  909 in Jonestown, plus the 4 in Georgetown (909+4=913) 
 *917 - "Victims" (total) (912 above + 5 that died at the PT airstrip  
 *918 - Total dead at all locales. 

 *Also, throw in the +/- 1 for the above regarding cult members dead depending on whether you count Patty Parks still as a cult member (had defected 2 hours before). 

 The article correctly lists the dead by location, and also explains causes of death, etc.