Being senior, to me, is best illustrated by a story:

Me: "Sometimes I feel like I'm psychic"

Co-worker: "How so?"

Me: "Many times on projects, I can tell at either the planning stages or the very early implementation steps if it's going to go well or be a disaster. e.g. people will say they love templated configs but they don't account for what can go wrong when there is a bug in the template etc etc"

Co-worker: "I don't think that's being psychic. That means you are a senior engineer who has seen so many projects that you can quickly pattern match on if the project is going to succeed or fail based on only the first 20% of the project."