This is exactly the kind of place to get the information you require to help you learn as well as become more proficient at asking the right questions.
Anyone can be and often is confused by the seeming overlap and interchangeing of the various terms and phrases used when discussing such tasks.
Basically a backup is just that, typically used to make copies of critical files and folders to a safe location (usually external but not always) to safeguard those items against accidental deletion, corruption or catastrophic loss as a result of hard drive failure. Backups can be performed by native software (like windows built-in backup) or any number of third party free and commercial software. Backups are not bootable and will often have a unique file extension, often only readable by the software that was used to create it.....
But not always, the term "back up" can and often does include a process which includes a full system (whole disk, all partitions) backup which is often called a drive image this method takes a point in time snapshot of your entire disk which again is not a bootable source and will often be in a format again only useable by the software which created it. Often these images can be mounted as is the case with a .VHD (virtual hard disk) (the format for a Windows Backup Image, or a .TIB (True Image Backup) (the format for an Acronis Backup Image) after mounting these types of images can be explored, copied from and in some instances even edited (contents altered and changed), kinda handy when just wanting to recover a single file. So now you should understand that an image can be a backup and a backup can be an image. The two terms are often inter-changeable, hence some confusion.
A clone is just that a clone, like Dolly the Sheep, an exact copy bit for bit of the source drive to another (destination) drive, of the same size or larger (but in some instances depending on the actual used space a smaller drive can be used). A cloned drive if done properly should boot exactly the same as the original drive (in a perfect world), but you also need to know that it's a roses complete with thorns kind of deal, in that if the original (source) drive contains corrupt files, bad sectors, etc. they get cloned as well. There are some methods to work around these problems but they can require some rather complicated steps. And again as is the case with all of these methods a clone is only good for and at a particular point in time. If you clone your boot drive today and swap out your motherboard tomorrow, chances are you will have problems booting from that clone, at the very least it will likely require reactivating windows again.
I hope this helps a little bit more getting things straight in your mind. But please don't be affraid or feel reticent about asking your questions here. That is our whole purpose for existing.
Regards
Randy