Question: What is the significance of taking vows in Buddhism?
Answer: There are several kinds of vows for Buddhists. Taking refuge in the Triple Gem is one kind. Committing to the Five Precepts is another, as is to the Eight Precepts, Bodhisattva Precepts and Monastic Precepts. And there are other independent vows. Vows express commitment to avoiding of evil, doing of good and purification of the mind. With strong commitment, there will be definite progress.
Question: How is taking of vows, for example to be vegan different from just abstaining from eating animal products?
Answer: With commitment, one is fully serious on that committed to, while without commitment, one is half-hearted. This further explains the major differences between commitment and non-commitment: http://thedailyenlightenment.
Question: When vows are taken, do they last for this lifetime or from life to life?
Answer: It depends on how the vows are committed to. For example, the Five Precepts are usually committed to for life, while the Eight Precepts for at least 24 hours.
Question: Are vows the same as precepts?
Answer: Precepts are moral guidelines adhered to as vows, but vows are not always precepts. For instance, the first precept of not killing is a vow, but Amituofo’s (Amitabha Buddha) 48 Great Vows are in terms of helping all beings to quickly attain Buddhahood; they are not precepts in terms of vowing not to do certain misdeeds.
Question: Is there any difference between taking a vow to not kill versus observing a precept to not kill?
Answer: Taking of precepts involve a ceremony to formally express commitment (i.e. vowing) for life (other than the Eight Precepts), while other vows might have no specific ceremony for expressing them, unless one chooses to vow formally.