To move an operative system from a HDD to another is not so simple. Copying all files to the other drive is not sufficient.
The best way is to use a dedicated software like Acronis True Image, that has the option to move all the contents from a disk to another keeping also all the MBR information needed to make the drive working correctly. It basically makes a 1:1 clone of all data (including also the MBR that is not copied when you simply move all files from a disk to another). Too bad, this software is not free, but you can use it in trial mode and then decide if you want to buy a license or not