Really, there isn't. Because usually you hear it like this: "Achieve work-life balance."
As a creative trying to build a business while taking care of my family and other relationships, I'm in a constant struggle to keep progress going on all fronts. And the word 'achieve' suggests that you can somehow get there if you only use the right time management techniques, or the latest to-do app, etc.
"Balance" as I see it is like your lane on the highway. You have a steering wheel, and you're constantly making little adjustments to stay where you are. If you don't pay attention you can drift to one side or the other, neglecting your other responsibilities. Also, there's no point where you're perfectly in your lane and can let up on the wheel. If you do, into the guardrail you go.
So don't get caught up reading every book/post about how to achieve this balance. Focus on making little adjustments to stay in the middle.
The road ahead never ends. The fun is how you drive down it.