'Any2Any' or just A2A, carries connotations of one-to-one, one-to-many, and even zero-to-any, to eventually anyone to anyone. Such A2A phenomenon could only take place in the virtual world, lending the grandness of anyone could communicate with anyone in the world without any pre-disposed connectedness assumuption. Could we make this also true in the physical world, the lifeworld?
O2O is of both, Online-to-Offline and the reverse, or is it truly a reverse in most senses? A2A is a characteristics of O2O.
O2O is not limited to that of the e-commerce scope, such as the notion of, where an online touchpoint of a product was established and final transactional behavior continued in offline at a brick-and-mortar store, or put in an order online after a visit at the physical store.
The notion is any directional hops from online to offline, and vice versa, the 'linkage' is intact. For example, in one simple scenario, where a face-to-face meeting (offline) will continue in the virtual meeting (online, such as using Zoom, or via Teams) with no loss.