Where each term comes from
Virtual receptionist predates the current AI wave by two decades. It described a person, employed by an answering company, who picked up your diverted calls, followed your greeting script and took messages: a receptionist, just not in your building. UK companies built substantial businesses on exactly this model, and still run it well.
AI receptionist is newer and describes software that holds the call itself: answering questions from a knowledge base, booking appointments, taking messages, and transferring callers by rules. No human answers, which is why it can answer every call at once, at any hour, at a flat price.
The muddle is commercial: virtual receptionist is what people search for, so software products adopt the older term, and human services increasingly bolt AI onto theirs. The label on the tin has stopped telling you what is inside it.