vow vs pledge

vow and pledge both are nouns.

Word	Noun	Adjective	Verb	Adverb
vow	Yes	No	Yes	No
pledge	Yes	No	Yes	No

As nouns, pledge is a hypernym of vow; that is, pledge is a word with a broader meaning than vow:

vow: a solemn pledge (to oneself or to another or to a deity) to do something or to behave in a certain manner
pledge: a binding commitment to do or give or refrain from something

Other hypernyms of vow include assurance.

As verbs, pledge is a hypernym of vow; that is, pledge is a word with a broader meaning than vow:

Other hypernyms of vow include plight.

vow (noun)	pledge (noun)
a solemn pledge (to oneself or to another or to a deity) to do something or to behave in a certain manner	a binding commitment to do or give or refrain from something
	a drink in honor of or to the health of a person or event
	someone accepted for membership but not yet fully admitted to the group
	a deposit of personal property as security for a debt

vow (verb)	pledge (verb)
make a vow; promise	promise solemnly and formally
dedicate to a deity by a vow	bind or secure by a pledge
	give as a guarantee
	propose a toast to
	pay (an amount of money) as a contribution to a charity or service, especially at regular intervals