valley vs dale

valley and dale both are nouns.

Word	Noun	Adjective	Verb	Adverb
valley	Yes	No	No	No
dale	Yes	No	No	No

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

valley: a long depression in the surface of the land that usually contains a river
dale: an open river valley (in a hilly area)

Other hyponyms of valley include glen, gully, holler, hollow, nullah, ravine, rift valley.

valley (noun)	dale (noun)
a long depression in the surface of the land that usually contains a river	an open river valley (in a hilly area)