What’s the difference? Which of them is worse?
Inapt is used usually to describe something which is not appropriate in a certain context.
Inept is used usually to describe something or someone which is poorly skilled or clumsy. This can be describing a person or their actions.
1 - “His joke about the dead lawyer was very inapt under the circumstances.”
2 - “He was completely inept at carrying out his work.”
There will be more explanations about the difference if you search under google as well. Hope this helps.