sun helmet vs pith helmet

sun helmet and pith helmet both are nouns.

Word	Noun	Adjective	Verb	Adverb
sun helmet	Yes	No	No	No
pith helmet	Yes	No	No	No

As nouns, sun helmet and pith helmet are synonyms defined as:

sun helmet and pith helmet: a lightweight hat worn in tropical countries for protection from the sun

Other synonyms of sun helmet include pith hat, topee, topi.

sun helmet (noun)	pith helmet (noun)
a lightweight hat worn in tropical countries for protection from the sun	a lightweight hat worn in tropical countries for protection from the sun