I think it may need some more time to formulate a reply than an 8 hr work day. Give it a little time and we may see some answers.
The main one that comes to mind for me would be the break schedule. Non-union rehearsals break when there is a reasonable moment to do so, rather than going by absolute time limits. The hours worked and days on/days off would also be precisely restricted, as opposed to staggered calls 7 days a week whenever you can nab somebody.
However, if you were doing AEA style in a college setting, you'd probably rehearse straight through any school vacations.
Working AEA style you cannot call the entire company for every rehearsal and then figure out what you're going to do with them once they arrive. The schedule needs to be set well in advance and specific calls need to be provided.
You'd have to warn everyone in advance if cameras were going to be present at a rehearsal.
Any nudity would have to be handled very very differently.
During tech & dress, you'd have to provide storage for valuables if you're running AEA style.
If an actor has a conflict for a paying gig, you have to let them go if you're doing AEA style rehearsals. Otherwise you'd just drop them and permanently replace them with another willing actor.
Some of the AEA provisions are tough to carry over without, y'know, AEA. If you really wanted to you could have a mock AEA deputy election at first rehearsal but it wouldn't really be necessary. You can't really bring AEA down on an actor who comes to rehearsal drunk, and can't have a union rep step in if the director is overworking the actors. So, you'd be able to TRY and enforce union protocol but it would be an approximation at best.