pith hat vs pith helmet

pith hat and pith helmet both are nouns.

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

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

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

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

pith hat (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