pruning shears vs shears

pruning shears and shears both are nouns.

Word	Noun	Adjective	Verb	Adverb
pruning shears	Yes	No	No	No
shears	Yes	No	No	No

As nouns, shears is a hypernym of pruning shears; that is, shears is a word with a broader meaning than pruning shears:

pruning shears: shears with strong blades used for light pruning of woody plants
shears: large scissors with strong blades

pruning shears (noun)	shears (noun)
shears with strong blades used for light pruning of woody plants	large scissors with strong blades