Easeus Disk Copy

I just used Easeus Disk Copy to make a copy of my main hard drive (C) onto a separate slave hard drive. I then removed my main hard drive (C) and tried to boot from the drive with the newly made copy on it. I removed the pin so it was now the master and not the slave. When booting up I got the message, "A disk read error occured. Press Ctrl + Alt + Del to restart" at the bottom of the black screen. I expected my system to boot up normally as it would from the original C: drive. What is wrong?

The only thing that I questioned when I was creating the copy with Easeus Disk Copy was a notification during the process that my source drive (my C: drive) was larger than the destination drive. I didn't think this mattered as the source drive only has 11.2 GB on its 150 GB capacity. The destination drive is 80 GB but maybe this is an issue.

Alternately, maybe I don't understand what it means to make a copy of a drive. Or maybe Easeus Disk Copy is not what I need. Is there software that will make an identical copy of my C: drive to another physical hard drive so that I could swap them out without any noticeable difference?

Thanks for any help or education.