system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why can't I click and drag my the entire contents of my 640gb hard drive(Windows included) to a 2nd 1tb hard drive and then only use that 2nd 1tb hard drive for my computer?

I suppose it might be better to explain this like I'm seventy five. Well, anyways, when I Google this, every result that's checked suggests using a program. Like Clonezilla for example. I'll probably do that, but I'd still like to know WHY I have to do that.
gpt
There are parts of Windows you don't see and the copy/drag-and-click won't work on them. These parts can include (but not limited to) the Disk Partition Table and Boot Sector - both are needed for Windows to work. The cloning programs have extra programming and can copy this information.