Windows 10 transfer confussion

I have 2 computers that had windows 8. I updated winows on one but not the other and my mom has been using it. I want to use the one with windows 10 and transfer all the files to the one with windows 8. What should I do?

ps: since the 2 computers have the same hardware can i clone the hardrive and use it on the other computer?

Hi,

You should use an external hard drive to transfer files from one PC to the other.