ticket agent vs seller

ticket agent and seller both are nouns.

Word	Noun	Adjective	Verb	Adverb
ticket agent	Yes	No	No	No
seller	Yes	No	No	No

As nouns, seller is a hypernym of ticket agent; that is, seller is a word with a broader meaning than ticket agent:

ticket agent: someone who sells tickets (e.g., theater seats or travel accommodations)
seller: someone who promotes or exchanges goods or services for money

Other hypernyms of ticket agent include marketer, trafficker, vender, vendor.

ticket agent (noun)	seller (noun)
someone who sells tickets (e.g., theater seats or travel accommodations)	someone who promotes or exchanges goods or services for money