riches vs gold

riches and gold both are nouns.

Word	Noun	Adjective	Verb	Adverb
riches	Yes	No	No	No
gold	Yes	Yes	No	No

As nouns, gold is a hyponym of riches; that is, gold is a word with a more specific, narrower meaning than riches:

Other hyponyms of riches include hoarded wealth, treasure.

riches (noun)	gold (noun)
an abundance of material possessions and resources	a deep yellow color
	something likened to the metal in brightness or preciousness or superiority etc.
	coins made of gold
	great wealth
	a soft yellow malleable ductile (trivalent and univalent) metallic element; occurs mainly as nuggets in rocks and alluvial deposits; does not react with most chemicals but is attacked by chlorine and aqua regia

riches (adjective)	gold (adjective)
	having the deep slightly brownish color of gold
	made from or covered with gold