lunch room是吃午饭的房间的意思，而canteen则是咖啡室的意思，区别可以从以下例子看出：

It is canteen only, if you want to have lunch, you should go to lunch room, they need to run their business. 这是咖啡室，如果你想吃午饭，你应该去午餐室，他们需要经营他们的生意。