The different is who's operating. In one case you only tell the car to get from a to b, in the other case you explicitly instruct the ai to do things. If the ai causes damages, I'd say it depends on what you prompted. Did you try to find a security hole in system X, or did you ask it for harmless information (in which case rather the ai vendor might be held accountable).

All this is not how the legal system might or might not work, of course.