Difference between a vow and an oath

Q 1: What is the difference between making a pledge, vowing and taking an oath? Which is more solemn? What is the meaning of a pledge? Does it have a Kaffarah (expiation)? What is it? What is the punishment of those who break it? If it does not have a Kaffarah, and a person makes a pledge in the following form, (Part No. 23; Page No. 120) "I make a pledge not to do this to you again", what should they do if they betray this pledge?

A: If a person makes a pledge, swears or takes an oath that you should do something, all these are oaths bound by intention that necessitate Kaffarah if broken, according to Allah's saying, Allâh will not punish you for what is unintentional in your oaths, but He will punish you for your deliberate oaths; for its expiation feed ten Masâkîn (poor persons), on a scale of the average of that with which you feed your own families, or clothe them or manumit a slave. But whosoever cannot afford (that), then he should fast for three days. That is the expiation for the oaths when you have sworn.