For Clone and Image, both work differently.
Image is copy everything to 1 file.
Clone is do a exact sector by sector copy.
It is not copying data, as what you think is.
It do not check or verify any data.
Both Image and Clone is doing on 1 partition of the HDD.
Some software Clone is based on the whole HDD to HDD, mostly for commercial use.
Mini Tools Partition is based on Clone partition.
I prefer to use this for cloning job and using as outside Windows; standalone & bootable.
Macrium Reflect Clone is by HDD.
Cloning will resolve your problem in copying files by files.
Also the timing could be faster than copying, as this depend on the system.
Image have 2 steps.
Step 1: Backup.
Step 2: Restore.
As for cloning from 320 GB HDD to 500 GB HDD.
Mini Tools Partition Wizard will copy the full 320 GB partition(s) to 500 GB HDD.
After completed, it can be resize to occupy the full 500 GB of the HDD storage.
I used Mini Tools Partition Wizard bootable version.
This software is not install in my laptop, since bootable version is available.
Software is available and free.
There are bootable version too.
It is available for both 32-bit and 64-bit Windows.
Best Free Partition Manager for Windows | MiniTool Partition Free
To create a bootable version, use this free USB boot disc.
Rufus - Create bootable USB drives the easy way
Your decision.
Regards
Eric.