leaf blade vs foliage

leaf blade and foliage both are nouns.

Word	Noun	Adjective	Verb	Adverb
leaf blade	Yes	No	No	No
foliage	Yes	No	No	No

As nouns, foliage is a hypernym of leaf blade; that is, foliage is a word with a broader meaning than leaf blade:

leaf blade: especially a leaf of grass or the broad portion of a leaf as distinct from the petiole
foliage: the main organ of photosynthesis and transpiration in higher plants

Other hypernyms of leaf blade include leaf, leafage.

leaf blade (noun)	foliage (noun)
especially a leaf of grass or the broad portion of a leaf as distinct from the petiole	(architecture) leaf-like architectural ornament
	the main organ of photosynthesis and transpiration in higher plants