spleen vs lymphoid tissue

spleen and lymphoid tissue both are nouns.

Word	Noun	Adjective	Verb	Adverb
spleen	Yes	No	No	No
lymphoid tissue	Yes	No	No	No

As nouns, lymphoid tissue is a hypernym of spleen; that is, lymphoid tissue is a word with a broader meaning than spleen:

spleen: a large dark-red oval organ on the left side of the body between the stomach and the diaphragm; produces cells involved in immune responses
lymphoid tissue: tissue making up the lymphatic system

Other hypernyms of spleen include lymphatic tissue.

spleen (noun)	lymphoid tissue (noun)
a large dark-red oval organ on the left side of the body between the stomach and the diaphragm; produces cells involved in immune responses	tissue making up the lymphatic system
a feeling of resentful anger