As seen from Android Device Manager 's description, it is basically a lost and found kind of app. It will try to locate your device whenever it is lost and helps to prevent ur data integrity. Also it can't track if there is no data connectivity.
But in case of WizzMe, you can have live updates of any person's location and also have an extra facility to track when user's data connection is off. Also after running it for a whole day it nearly consumed around 2% percent of the battery. It has this feature of enabling gps and wifi/mobile data on permission basis (dont know whether other tracking apps provide this functionality)...Enabling and disabling tracking permissions as required by the user.Partial and Full permission kind of permissions giving user more flexibility from whom he/she can be tracked. More info can be found in Apps FAQ section inside after login.......