Copying a c drive to another c drive

Trying to do an *exact* copy of the c drive from my desktop to the c drive on my laptop, everything including the os. I put the c drive from the desktop into a caddy, connected it to the laptop and tried to do it, but afterwards, the os kept going in a loop trying to start. I have a flight to catch later today and trying to get it all sorted before then, so, what is the right way to do it please?