Is a promise ring the same as an engagement ring?
No. A promise ring is a pledge of commitment; an engagement ring marks an intention to marry.
Ring etiquette · Meaning
A promise ring and an engagement ring both symbolize commitment, but they mean different things and are usually very different in cost and design.

A promise ring says 'I am committed to you' and may come years before any proposal. An engagement ring is given with a proposal of marriage.
Promise rings are often worn on the ring finger of the right hand, or the left hand before engagement. Engagement rings are traditionally worn on the left ring finger in the US.
Promise rings are typically simple bands or small stones. Engagement rings usually feature a center diamond and cost considerably more.
Many couples keep the promise ring and move it to the right hand, or stack it, once the engagement ring arrives.
No. A promise ring is a pledge of commitment; an engagement ring marks an intention to marry.
Promise rings are usually modest — often a small fraction of an engagement ring budget.
Yes, if both people agree. What matters is the meaning you give it.
Anyone in a committed relationship. Couples sometimes exchange them with each other.