To an engineer, good enough means perfect. With an artist, there's no such thing as perfect.

This quote is saying that when an engineer is working on something, they strive to make it perfect – they won’t be satisfied until it’s as good as it can possibly be. On the other hand, an artist often has no idea of what perfect would look like, as they are looking to create something unique. So they may never feel like their work is “perfect” but they may still be satisfied with the outcome.