tumor vs neoplasm

tumor and neoplasm both are nouns.

Word	Noun	Adjective	Verb	Adverb
tumor	Yes	No	No	No
neoplasm	Yes	No	No	No

As nouns, tumor and neoplasm are synonyms defined as:

tumor and neoplasm: an abnormal new mass of tissue that serves no purpose

Other synonyms of tumor include tumour.

tumor (noun)	neoplasm (noun)
an abnormal new mass of tissue that serves no purpose	an abnormal new mass of tissue that serves no purpose