One is 'Exclusive'. Ok, smart answer done with.
This is explained in the wiki
http://wiki.radioreference.com/index..._Air_Interface
"P25 CAI means a digital system. P25 CAI is a digital voice (modulation) type and therefore can be used on conventional channel radio system or in a trunking radio system. System type is not dependent on the use of P25 CAI except in the case of a Project 25 Trunking Radio System; in that specific case only P25 CAI modulation is used (no analog allowed.)"
"P25 CAI Exclusive means a 9600 bps control channel. P25 CAI is not related to the bps rate of any trunking system at all. P25 CAI is used on several Motorola ASTRO systems (3600 bps) both shared with analog talk groups or as an exclusive modulation type. Examples of the latter are the South Dakota State TRS and the Ohio State MARCS systems. Neither of these systems are Project 25 systems, but both are P25 CAI exclusive."