sun hat vs topee

sun hat and topee both are nouns.

Word	Noun	Adjective	Verb	Adverb
sun hat	Yes	No	No	No
topee	Yes	No	No	No

As nouns, topee is a hyponym of sun hat; that is, topee is a word with a more specific, narrower meaning than sun hat:

sun hat: a hat with a broad brim that protects the face from direct exposure to the sun
topee: a lightweight hat worn in tropical countries for protection from the sun

Other hyponyms of sun hat include pith hat, pith helmet, sun helmet, topi, sunbonnet.

sun hat (noun)	topee (noun)
a hat with a broad brim that protects the face from direct exposure to the sun	a lightweight hat worn in tropical countries for protection from the sun