shovel vs dredge

shovel and dredge both are nouns.

Word	Noun	Adjective	Verb	Adverb
shovel	Yes	No	Yes	No
dredge	Yes	No	Yes	No

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

Other hyponyms of shovel include backhoe, steam shovel.

shovel (noun)	dredge (noun)
a hand tool for lifting loose material; consists of a curved container or scoop and a handle	a power shovel to remove material from a channel or riverbed
a fire iron consisting of a small shovel used to scoop coals or ashes in a fireplace
a machine for excavating
the quantity a shovel can hold

shovel (verb)	dredge (verb)
dig with or as if with a shovel	remove with a power shovel, usually from a bottom of a body of water
	search (as the bottom of a body of water) for something valuable or lost
	cover before cooking