bough vs limb

bough and limb both are nouns.

Word	Noun	Adjective	Verb	Adverb
bough	Yes	No	No	No
limb	Yes	No	No	No

As nouns, limb is a hypernym of bough; that is, limb is a word with a broader meaning than bough:

Other hypernyms of bough include tree branch.

bough (noun)	limb (noun)
any of the larger branches of a tree	any projection that is thought to resemble a human arm
	the graduated arc that is attached to an instrument for measuring angles
	either of the two halves of a bow from handle to tip
	one of the jointed appendages of an animal used for locomotion or grasping: arm, leg, wing, flipper
	(astronomy) the circumferential edge of the apparent disc of the sun or the moon or a planet
	any of the main branches arising from the trunk or a bough of a tree