I am studying Japanese オノマトペ and I came across two that are very similar. The definitions I found online, and the examples sentences in the book don't align, so I am confused about the 使い方。
On this website, they say that へとへと describes a more exhausted condition than くたくた. They describe へとへと as "so tired that you can't get off the floor" and くたくた as "Tired, but if you rest for a while, you will be good again", but, in the JLPT book that I am studying from, the example sentences make it sound like the difference is between physical exhaustion and mental exhaustion.
So what actually is the difference?