"to answer the question is too hard" - Command. They will not answer because of difficulty. "the question is so hard that I can't answer" - a more polite / apologizing way to say it, as if they are sorry they cannot answer. It is not exactly the same but close enough that they can have the same meaning. The only difference is the emphasis. Question 1 emphasizes 'Answer' and the second emphasizes 'Question'. I hope that's not too complicated!

Can you explain？

What about “it‘s too hard to answer the question” ？

In English " The question is too hard to answer" , "to answer the question is too hard" and " the question is so hard that I can't answer" all mean the same thing. The first phrase "The question is too hard to answer" sounds the most natural, and some people might say "The question is too difficult to answer."