Originally Posted by arthwollipot
I think my attempt was pretty decent: we can understand something in a way that works very well empirically, even to the point that no observation or experiment that we're currently capable of can contradict it, yet that understanding can be unclear or even contradictory at a fundamental level.
An example is gravity. GR works great on it's own, and it's also completely consistent with experiment. But we know the universe is quantum mechanical in nature, yet when we try to apply the principles of quantum mechanics to gravity, we get results that don't work (infinities that can't be got rid of through the normal methods of renormalization, for instance).
So we understand gravity very well, but on a fundamental level there's something we're missing.
Or to take it a step back, Newton also understood gravity pretty well, but not on a fundamental level. Einstein came much closer to a fundamental level, and if my above paragraphs were wrong we could say that Einstein understood it fundamentally, but that doesn't mean that Newton didn't understand it at all.
Anyway, that seems like a meaningful distinction to me.
But maybe you were complaining not that no one answered your question but that the person you asked didn't answer it...