for fear that,in case,lest引导目的状语从句什么有区别吗

for fear that,in case,lest引导目的状语从句什么有区别吗我的语法书上出现这样两个例子.不知道有什么用法上的区别：The boy hid himself behind the tree in case/for fear that his father should see him.Take your raincoat in case/lest it should rain.