memory vs memory trace

memory and memory trace both are nouns.

Word	Noun	Adjective	Verb	Adverb
memory	Yes	No	No	No
memory trace	Yes	No	No	No

As nouns, memory trace is a hyponym of memory; that is, memory trace is a word with a more specific, narrower meaning than memory:

memory: something that is remembered
memory trace: a postulated biochemical change (presumably in neural tissue) that represents a memory

Other hyponyms of memory include reminiscence, recollection, engram, confabulation, screen memory.

memory (noun)	memory trace (noun)
an electronic memory device	a postulated biochemical change (presumably in neural tissue) that represents a memory
the power of retaining and recalling past experience
the cognitive processes whereby past experience is remembered
something that is remembered
the area of cognitive psychology that studies memory processes