To answer the quesion ...
I just want to know that is there any way to copy a file from one Ext4 partition to other without using terminal?
You can use Nautilus if you copy the file over with the user name that owns the destination you want to copy the file to. That user needs to own that location or needs to be part of a group owning that location.
If you want any user to be able to do that: no, not without changing. It would be a security problem if you could. This will at least require you to one time change the ownership of the destination and doing that with a terminal would be the easiest. And the only user that can do this needs to be an admin of your system (someone that can use "sudo").
Some links to help you out (but they will rely on the terminal):
In case you have questions regarding terminal commands: feel free to drop into AskUbuntu Chat (20 reputation required). There will always be someone there willing to help.