lay-by vs rest area

lay-by and rest area both are nouns.

Word	Noun	Adjective	Verb	Adverb
lay-by	Yes	No	No	No
rest area	Yes	No	No	No

As nouns, lay-by and rest area are synonyms defined as:

lay-by and rest area: designated paved area beside a main road where cars can stop temporarily

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

lay-by (noun)	rest area (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