Assuming you're referring to ROM and RAM they are the permanent and temporary memory inside your computer. ROM refers to READ ONLY MEMORY and is generally "burned" or stored semi-permanently on a computer chip designed for that purpose. It contains the information and programs your computer needs to wake up and begin its tasks; the things stored in ROM are not lost when the computer is on or off. RANDOM ACCESS MEMORY refers to the temporary RAM memory inside your computer and is the memory your computer uses to perform the day to day tasks of computing. It's temporary because when you switch off your computer, whatever is in there, goes away. Computers also commonly have some type of removable media (like thumb drives, floppy discs, cd's, etc...) and fixed storage media like a hard drive to store data, software and the like.
