From this answer,
Android Alarm What is the difference between four types of Alarm that AlarmManager provides and when to use what?
Also this tells the difference in the types of Alarms,
It will trigger since the boot time. Say if you set to 300000 then the alarm will trigger every 5 minutes and will not take the current time in consideration.
It will trigger as per the clock time meaning does not take boot time in consideration and will trigger at time as specified.
To wake up your device use this,
alarmManager.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, triggerTime, mInterval, pendingIntent);
else use this if you don't want to wake up the device
alarmManager.setRepeating(AlarmManager.ELAPSED_REALTIME, triggerTime, mInterval, pendingIntent);