lymphedema vs oedema

lymphedema and oedema both are nouns.

Word	Noun	Adjective	Verb	Adverb
lymphedema	Yes	No	No	No
oedema	Yes	No	No	No

As nouns, oedema is a hypernym of lymphedema; that is, oedema is a word with a broader meaning than lymphedema:

lymphedema: swelling (usually in the legs) caused by lymph accumulating in the tissues in the affected areas
oedema: swelling from excessive accumulation of watery fluid in cells, tissues, or serous cavities

Other hypernyms of lymphedema include dropsy, edema, hydrops.

lymphedema (noun)	oedema (noun)
swelling (usually in the legs) caused by lymph accumulating in the tissues in the affected areas	swelling from excessive accumulation of watery fluid in cells, tissues, or serous cavities