sense datum vs sense impression

sense datum and sense impression both are nouns.

Word	Noun	Adjective	Verb	Adverb
sense datum	Yes	No	No	No
sense impression	Yes	No	No	No

As nouns, sense datum and sense impression are synonyms defined as:

sense datum and sense impression: an unelaborated elementary awareness of stimulation

Other synonyms of sense datum include aesthesis, esthesis, sensation, sense experience.

sense datum (noun)	sense impression (noun)
an unelaborated elementary awareness of stimulation	an unelaborated elementary awareness of stimulation