SD card copier partitions the target drive, then copies over the data. This allows you to copy a drive to a different sized drive, and you can use a smaller capacity drive as long as the data fits. Note that SD card copier works just fine for those of us who USB boot and go HD to HD.
Now if you want to make a true image of your card or HD, I suggest gnome disk utilities (sudo apt-get install gnome-disk-utilities) which allows you to create an image, then restore it. You can also use this to create a new SD card from a Raspian image. You can run gnome-disks from the terminal once installed, or search your menu for "disks". This app, along with gparted, are extremely useful.
If you just want to back up data, then take a look at Grsync...the GUI front end for rsync.