What is the format 7"+CDR?

When you buy a 7"+CDR, you will receive the original 7" along with a copy of the same music on a CDR (recordable CD). This will allow you to play the music in a regular CD player (or on a computer) in addition to listening to the music on a record player.

Are CDRs (recordable CDs) identical to 'normal' CDs?

Music CDs you commonly find in stores are pressed from a glass mold. CDRs are burned with a laser on a home computer and typically look slightly different with the disc being green, gold or blue in color instead of being silver. And while not physically identical to a CD your normally find in stores, CDRs work just the same and will play in any CD player you have.