I can tell you what the difference isn't. It's neither about age nor experience. And I'm saying this as an old fart who has been doing this for 25+ years. Sure

I can tell you what the difference isn't. It's neither about age nor experience. And I'm saying this as an old fart who has been doing this for 25+ years. Sure, time helps, if you learn from your mistakes, both in engineering and life itself. But I've seen 40 year old developers who I would consider juniors in every way that matters, and 20-somethings who I would trust to take the role of lead developer.