office是办公室的意思，而department则是部门的意思，区别可以从以下例子看出：
If you want to complain this matter, you can go to that department, its office just in the 2nd floor. 如果你想投诉这件事，你可以去那个部门，它的办公室就在二楼。
水利万物而不争,
而万物莫能与之争。
