AIS system does not communicate any globally available data, whereas LRIT is a globally available, satellite-supported system which meets the requirements of the authorities of having access to the data of individual ships globally and at any time. Time and frequency must be freely configurable by the authority requesting the data at all times. Manipulation by ships (e.g., entering incorrect data) must be eliminated.
One of the most important differences between LRIT and AIS, however, is that AIS is a so-called broadcast system, i.e., is public, whereas LRIT data are only available to institutions which have a (governmental) entitlement to the data and guarantee the confidentiality of these data.
Another main difference is that AIS is a Collision avoidance system mandated by the IMO whereas LRIT is a Reporting system mandated by the IMO.