So, they are similar meanings; we usually use the word " restraint" when we are talking about controlling a person – someone who is out of control, someone who needs to be controlled.

所以，它们是相似的意思；当我们谈论控制一个人时， 我们通常使用“约束” 这个词——一个失控的人， 一个需要被控制的人。