If you bake an AO map it isn’t interactive. It’s just a greyscale map of ambient lighting. Some renderers can mask it based on the amount of direct light hitting the surface.
The difference between AO and cavity is that cavity tends to cover smaller details and isn’t actually dependant on lighting just the… cavities higher frequency of geometric detail. For example, if you’d bake a cavity and AO on a head mesh the cavity map will have pores and wrinkles, but it won’t have shadows in places that woud actually get occluded, like the inside of the mouth, nostrils, ears and eye sockets. In cavity map there also isn’t any interaction between meshes that are close by that should have AO.
Cavity on left and AO on the right:
