Copal and Kauri gum

Copal noun - A brittle aromatic resin used in varnishes.

Kauri gum and copal are semantically related. In some cases you can replace phrase "Kauri gum" with "Copal", this terms are similar.

Kauri gum noun - Resin of the kauri trees of New Zealand; found usually as a fossil; also collected for making varnishes and linoleum.

Copal and kauri gum are semantically related. Sometimes you can use "Copal" instead a noun phrase "Kauri gum".