Separations can happen for several reasons and they have different terms, I recognize that most people associate "fired" with incompetence or misconduct and that likely wasn't the case here[1].

Generally, with senior leaders, they have a set of objectives that they are tasked with working toward, and every year is a negotiation over whether or not they are meeting their objectives. When they aren't meeting those objectives (or perhaps enough of those objectives) then there is a discussion about next steps. Which is a euphemism for "this isn't working for us, we need to replace you with someone who can meet these objectives."

Now is that getting fired? or laid off? I think it's semantics. At the end of the day you don't have a job with the company any more. Few senior leaders that I've interacted with have ever called out the company for telling them they were going to lose their job. If you have reached that level you should have the maturity to understand that it is a fact of life that this happens. Scott McNealy used to send congratulations to people who were promoted into the senior ranks with "One step up, one step closer to the door." That reflected the reality that there are few alternative positions within a company for someone who is leading a big chunk of the company.

When the separation is the idea of the employee (which is to say they quit), the notification pattern seems proactive on the employee's side. A press release that the employee is moving on and that the company is working on finding a successor, and then sometime later we get the "I'm actually leaving now, and here is my successor." press release. But there is no hard and fast rule.

Bottom line is that the term 'fired' has the connotation of malfeasance and that doesn't seem to be the case here, I should have used "likely involuntary separation" but that seems a bit wordy, although it avoids the baggage of the word fired.

[1] As we can see from documents about Andy Rubin's departure, all of the press at the time read like Andy was just moving on to bigger and better things, when in fact he was being separated from the company because of credible accusations of sexual harassment. My point being that we on the outside can't know why a senior leader is leaving really, the copy in the press releases is carefully crafted regardless of the actual reasons.