To me, the difference is what you're communicating when you tell a kid, "You're so smart!"

- "You know a lot of things." - When a child confuses high ability with knowing things, anytime they run into a challenge, they decide they're a fraud.

- "You learn very quickly." - This message is about potential skills, not acquired skills, and as such teaches a child that they have the ability to excel... if they put in the effort.

One is a healthy message, and one is not. The first child will wilt on discovering a challenge, where the second will be fortified to persevere, confident that they can rise to the challenge.