mattock vs pick mattock

mattock and pick mattock both are nouns.

Word	Noun	Adjective	Verb	Adverb
mattock	Yes	No	No	No
pick mattock	Yes	No	No	No

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

mattock: a kind of pick that is used for digging; has a flat blade set at right angles to the handle
pick mattock: a versatile hand tool that combines a pick and an adze, used for grubbing in hard soils and rocky terrain.

Other hyponyms of mattock include pick-mattock.

mattock (noun)	pick mattock (noun)
a kind of pick that is used for digging; has a flat blade set at right angles to the handle	a versatile hand tool that combines a pick and an adze, used for grubbing in hard soils and rocky terrain.