slater vs sow bug

slater and sow bug both are nouns.

Word	Noun	Adjective	Verb	Adverb
slater	Yes	No	No	No
sow bug	Yes	No	No	No

As nouns, sow bug is a hyponym of slater; that is, sow bug is a word with a more specific, narrower meaning than slater:

slater: any of various small terrestrial isopods having a flat elliptical segmented body; found in damp habitats
sow bug: terrestrial isopod having an oval segmented body (a shape like a sow)

Other hyponyms of slater include pill bug.

slater (noun)	sow bug (noun)
any of various small terrestrial isopods having a flat elliptical segmented body; found in damp habitats	terrestrial isopod having an oval segmented body (a shape like a sow)