The difference is that the genuine Arduino uses the DIP package version of the processor and has an ATmega16U2 for the USB interface. The cheaper "clone" uses a TQFP package version of the processor and has a CH340G chip for the USB.
For the "clone" you would have to use a different driver for the USB interface than the standard one used for the genuine UNO. Once programmed, the two boards will behave identically.
The processor package doesn't make any difference unless you need to remove and replace it.
Thanks so much MLXXXp!
This is my first time I have to program an arduino .. my doubt is, the commands that I have to load are the same for both "arduino" or if I take the cheap one I should change something? Let's say that in practice I did not understand if there are any real differences.
The commands will be identical for both boards. You just need to use a different USB driver for each. The driver for the real UNO should be installed when you install the Arduino IDE. For Windows or Mac, I'm not sure what you have to do for the CH340G driver for the other board. I use Ubuntu Linux and the driver is there automatically.
The latest Uno I bought was a very cheap one, £2.55 from China including postage. No problem with driver so it must be installed in Windows 10
The latest Uno I bought was a very cheep one, £2.55 from China including postage. No problem with driver so it must be installed in Windows 10