scratchpad vs computer memory

scratchpad and computer memory both are nouns.

Word	Noun	Adjective	Verb	Adverb
scratchpad	Yes	No	No	No
computer memory	Yes	No	No	No

As nouns, computer memory is a hypernym of scratchpad; that is, computer memory is a word with a broader meaning than scratchpad:

scratchpad: (computer science) a high-speed internal memory used for temporary storage of preliminary information
computer memory: an electronic memory device

Other hypernyms of scratchpad include computer storage, memory, memory board, storage, store.

scratchpad (noun)	computer memory (noun)
(computer science) a high-speed internal memory used for temporary storage of preliminary information	an electronic memory device