layby vs rest stop

layby and rest stop both are nouns.

Word	Noun	Adjective	Verb	Adverb
layby	Yes	No	No	No
rest stop	Yes	No	No	No

As nouns, layby and rest stop are synonyms defined as:

layby and rest stop: designated paved area beside a main road where cars can stop temporarily

Other synonyms of layby include lay-by, pull-off, rest area.

layby (noun)	rest stop (noun)
designated paved area beside a main road where cars can stop temporarily	designated paved area beside a main road where cars can stop temporarily