secretary vs top dog

secretary and top dog both are nouns.

Word	Noun	Adjective	Verb	Adverb
secretary	Yes	No	No	No
top dog	Yes	No	No	No

As nouns, top dog is a hypernym of secretary; that is, top dog is a word with a broader meaning than secretary:

secretary: a person who is head of an administrative department of government
top dog: a person who is in charge

Other hypernyms of secretary include chief, head.

secretary (noun)	top dog (noun)
a desk used for writing	a person who is in charge
an assistant who handles correspondence and clerical work for a boss or an organization
a person who is head of an administrative department of government
a person to whom a secret is entrusted