AirWave shows a less number of connected Aruba APs than the controller is reporting. The LAN MAC address of the missing AP(s) ends in ":FE" or ":FF".
This is an AOS defect that causes the SNMP response for wlanAPIpAddress OID to not contain any device with LAN MAC that ends in "FE" and "FF". The details are recorded in defect number 54939. AOS release 188.8.131.52 and later contains the fix.