When you say "from domain to another", I assume you mean hosts.
If you have ftp or sftp, you can download the files and upload to the other.
If you have access to ssl, you can use rsync... or, you can move the file to the webroot and download it from the other machine using wget...
I recently had to move my website, what I did was compress everything in tar and saved it in my webroot
Then I used: wget https://www.domain.com/myFiles.tar from another server to download the files. You can also sftp it from one site to the other directly but I've never done that before.
Please, forgive me for jumping into this conversation, but I, too, want to copy one domain into another.
Bottom Line: When we bought Louisvilleitalians.net for my client, last year, we also bought Louisvilleitalians.org, but when I set up the domain for the .net as the primary domain, I haven't had time to get to work on the .org, yet....luckily for me, the client wants "both sites to have exactly the same information" but, I'm concerned about SAFELY COPYING EVERYTHING BETWEEN SITES.
That's where your expertise comes in...how can I do that, please?
Cheryl Graham, firstname.lastname@example.org
Have you thought about just forwarding the domain to the already functioning site so you only have to manage one site?