hydrothorax vs congestion

hydrothorax and congestion both are nouns.

Word	Noun	Adjective	Verb	Adverb
hydrothorax	Yes	No	No	No
congestion	Yes	No	No	No

As nouns, congestion is a hypernym of hydrothorax; that is, congestion is a word with a broader meaning than hydrothorax:

hydrothorax: accumulation of fluid in the pleural cavity (the space between the lungs and the walls of the chest) often resulting from disease of the heart or kidneys
congestion: excessive accumulation of blood or other fluid in a body part

hydrothorax (noun)	congestion (noun)
accumulation of fluid in the pleural cavity (the space between the lungs and the walls of the chest) often resulting from disease of the heart or kidneys	excessive accumulation of blood or other fluid in a body part
	excessive crowding