AAI doesn't use the AIARE standard. Both AAI and AIARE follow the AAA guidelines for classes, which can be found on the education page at
www.americanavalancheassociation.org
The requirement is to have 50/50, class and field, and to have at least 24 hours of curriculum of both. From personal experience, any AAI class has top-notch and experienced instructors who have been at it a LONG time and know their stuff. Your AIARE instructor would probably be Jonathan Shefftz, who also knows his stuff. (hi js) I agree that the big difference is the instructor, but the overall level of expertise in the class makeup plus the level of interest in the terrain and the snowpack are also important.