Pith hat and Sun hat

Pith hat noun - A lightweight hat worn in tropical countries for protection from the sun.

Sun hat and pith hat are semantically related. In some cases you can use "Sun hat" instead a noun phrase "Pith hat".

Sun hat noun - A hat with a broad brim that protects the face from direct exposure to the sun.

Pith hat and sun hat are semantically related. Sometimes you can replace phrase "Pith hat" with "Sun hat", this phrases are similar.