malacia vs osteomalacia

malacia and osteomalacia both are nouns.

Word	Noun	Adjective	Verb	Adverb
malacia	Yes	No	No	No
osteomalacia	Yes	No	No	No

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

malacia: a state of abnormal softening of tissue
osteomalacia: abnormal softening of bones caused by deficiencies of phosphorus or calcium or vitamin D

malacia (noun)	osteomalacia (noun)
a state of abnormal softening of tissue	abnormal softening of bones caused by deficiencies of phosphorus or calcium or vitamin D