Realtor vs estate agent

Realtor and estate agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
Realtor	Yes	No	No	No
estate agent	Yes	No	No	No

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

Realtor: a real estate agent who is a member of the National Association of Realtors
estate agent: a person who is authorized to act as an agent for the sale of land

Other hypernyms of Realtor include house agent, land agent, real estate agent, real estate broker.

Realtor (noun)	estate agent (noun)
a real estate agent who is a member of the National Association of Realtors	a person who is authorized to act as an agent for the sale of land