disagreement - the speech act of disagreeing or arguing or disputing

confrontation - discord resulting from a clash of ideas or opinions

variance, division - discord that splits a group

conflict - a state of opposition between persons or ideas or interests; "his conflict of interest made him ineligible for the post"; "a conflict of loyalties"

disunity - lack of unity (usually resulting from dissension)

divide - a serious disagreement between two groups of people (typically producing tension or hostility)