telegraphist vs telegraph operator

telegraphist and telegraph operator both are nouns.

Word	Noun	Adjective	Verb	Adverb
telegraphist	Yes	No	No	No
telegraph operator	Yes	No	No	No

As nouns, telegraphist and telegraph operator are synonyms defined as:

telegraphist and telegraph operator: someone who transmits messages by telegraph

Other synonyms of telegraphist include telegrapher.

telegraphist (noun)	telegraph operator (noun)
someone who transmits messages by telegraph	someone who transmits messages by telegraph