What is a hotel room upgrade? (Specific information)

First of all, room upgrade has two meanings:

1 interior decoration: after the hotel is opened for a certain number of years, the room facilities will be damaged and aged with consumption. In order to meet the needs of the market and guests, the room will be renovated and the hotel hardware facilities will be updated. Also called room upgrade.

2 solving complaints: this is more complicated. Simply put, you booked a hotel room, but for various reasons, the hotel didn't arrange it for you. When you arrived at the hotel, the room you reserved was gone. At this time, in order to solve your problem, the hotel upgraded your room, that is, for example, you booked a standard room and upgraded to a deluxe standard room or a better room, but the standard room still needs to be charged. That's what it means.

I don't have the specific information for the time being. The second point belongs to the unwritten rules of the hotel industry, in order to give guests better arrangements!