sex-change operation vs surgery

sex-change operation and surgery both are nouns.

Word	Noun	Adjective	Verb	Adverb
sex-change operation	Yes	No	No	No
surgery	Yes	No	No	No

As nouns, surgery is a hypernym of sex-change operation; that is, surgery is a word with a broader meaning than sex-change operation:

sex-change operation: surgical procedures and hormonal treatments designed to alter a person's sexual characteristics so that they resemble those of the opposite sex
surgery: a medical procedure involving an incision with instruments; performed to repair damage or arrest disease in a living body

Other hypernyms of sex-change operation include operation, surgical operation, surgical procedure, surgical process.

sex-change operation (noun)	surgery (noun)
surgical procedures and hormonal treatments designed to alter a person's sexual characteristics so that they resemble those of the opposite sex	a medical procedure involving an incision with instruments; performed to repair damage or arrest disease in a living body
	a room in a hospital equipped for the performance of surgical operations
	a room where a doctor or dentist can be consulted
	the branch of medical science that treats disease or injury by operative procedures