区别就是两者都是名词instance +介词短语，两者都是可以表示……的实例，但用法是不一样的，具体的不同如下
instance for中文意思是……的实例
Case instance for all objects contained in the case.案例实例，设置应用于案例中包含的所有对象。
instance of中文意思是（类的）实例；（某类别的）实体
Then there are the liberals, with whom I would normally side, who protest that government regulation would be yet another instance of interference in our lives.
