rhizotomy vs surgical operation

rhizotomy and surgical operation both are nouns.

Word	Noun	Adjective	Verb	Adverb
rhizotomy	Yes	No	No	No
surgical operation	Yes	No	No	No

As nouns, surgical operation is a hypernym of rhizotomy; that is, surgical operation is a word with a broader meaning than rhizotomy:

rhizotomy: surgical procedure in which spinal nerve roots are cut; done (anterior roots) to relieve intractable pain or (posterior roots) to stop severe muscle spasms
surgical operation: a medical procedure involving an incision with instruments; performed to repair damage or arrest disease in a living body

Other hypernyms of rhizotomy include operation, surgery, surgical procedure, surgical process.

rhizotomy (noun)	surgical operation (noun)
surgical procedure in which spinal nerve roots are cut; done (anterior roots) to relieve intractable pain or (posterior roots) to stop severe muscle spasms	a medical procedure involving an incision with instruments; performed to repair damage or arrest disease in a living body