Yep - that is the issue. You can define it however you want so it's fairly arbitrary. To answer your question - given it was a major life direction change, I consider it a career change. I'd say a career change probably involves a similar life change in all cases.
My professional white-collar wife has done 3 changes already and we're barely middle-aged. I've done 2 myself (factory worker -> Researcher -> Engineer).
My Mom has done about 5-6. My dad 1. My mother in law has done at least 5, and my father in law at least 3.
My brother has done 2 (soldier -> sales -> design). My 4 bros-in-law have done at least 3 each (all starting with soldier).
Sis in law has done 0. My sisters are 3,2 and are still young.
Does my story cancel yours? no, but the story isn't clear either.