The mass of an object is the amount of matter it contains while volume is the amount of space it takes up. Mass should not be confused with weight, which is the measure of the gravitational force on an object.
The fundamental unit for mass in the metric system is the gram and in the SI system is the kilogram. The English system does not have a unit for mass; rather, it uses ounces, pounds and tons as units of weight. The metric system uses the liter as its base unit for volume. The base using in the SI system is the cubic meter. In the English system, volume is measure in fluid ounces, cups, pints, quarts and gallons.