ISO file = a standard fromat for storing the contents of a CD disc so that it can be burned from a file
image = proprietary archive (sort of a zip) of hard drive partitions, the format is vendor-specific (Ghost != Drive Image)
copy = transfer contents to another hard drive as file system + individual files not a single archive / image
boot disk = floppy or special CD that includes a boot sector telling it auto-run an OS (typically some DOS) when the computer is restarted.
For more, google is your friend and/or ask a specific question.