Looking at the wikipedia page, I'd say "ego death" sounds like a very different concept. What the parent posters are talking about is when you have two persona

Looking at the wikipedia page, I'd say "ego death" sounds like a very different concept. What the parent posters are talking about is when you have two personalities: the original and the mask, but the mask stays on so long it becomes the new permanent personality. The original "ego" is gone and already replaced. "ego death" sounds like a loss of the only personality. There's no alternate.