What is the difference between 義務and 本分?

Question

Now, I try to brush up my vocabulary in Japanese.
In dictionary, both 義務 and 本分 mean "duty". Is there any differences in usage?
And can I use 本分 instead of 義務 in following sentence?

私の公の行為を当局者以外に説明する義務はないと思う.

with regards,

Answer 1

• 義務 is a general term meaning "obligation".

国民には納税の義務がある
船長は自分より先に全ての客を避難させる義務がある

• 本分 particularly means "duty", or "activity that someone is supposed to be spending most of their time on according to their title/occupation", and does not necessarily have the strong meaning of "obligation".

学生の本分は学ぶことである

Using 本分 in your example is completely wrong.