Last week, I flew DTW-TPE through NRT and of the five trips this year, it was the first time that the NRT-TPE leg was on the original DL 275 from DTW. The other four times, the equipment changed from the 747 to either a A330 or 777. I was sitting in 77K the during the DTW-NRT leg, the upper deck was completely full and it was the standard BE service. I reboarded and retook seat 77K for the NRT-TPE leg and noticed that the BE service used the carts with the UD only half full. I thought it was odd, but maybe the FA was comfortable using the cart.