Hot concentrated KMnO4
Oxidative cleavage occurs. The double bond is broken to which oxygen atoms are going to be added forming a carboxylic acid group at each. Thus breaking the cyclic structure, forming hexane-1,6-dioic acid.
Cold dilute KMnO4
Oxidative addition occurs where the pi bonds of the double bonds break to have hydroxyl functional groups attached to both carbons that used to participate in the double bond. This mechanism forms cyclohexane-1,2-diol.