ocher vs yellow ocher

ocher and yellow ocher both are nouns.

Word	Noun	Adjective	Verb	Adverb
ocher	Yes	Yes	No	No
yellow ocher	Yes	No	No	No

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

ocher: any of various earths containing silica and alumina and ferric oxide; used as a pigment
yellow ocher: pigment consisting of a limonite mixed with clay and silica

Other hyponyms of ocher include sinoper, sinopia, sinopis, yellow ochre.

ocher (noun)	yellow ocher (noun)
a moderate yellow-orange to orange color	pigment consisting of a limonite mixed with clay and silica
any of various earths containing silica and alumina and ferric oxide; used as a pigment

ocher (adjective)	yellow ocher (adjective)
of a moderate orange-yellow color