Many people are not sure whether to purchase a propane tank in pounds or ounces. The main difference between the two is that a pound tank will last twice as long as an ounce tank. However, an ounce tank is more portable and easier to store. If you are only going to be using your propane tank for a small project, then an ounce tank may be the better option for you. If you plan on using your propane tank for larger projects, then a pound tank would be a better choice.