Difference Between Volume and Capacity
The terms Volume and capacity are scientific terms that may appear to mean the same thing as both of them are related to occupying a space by any object/substance, but in reality, there is a big difference in the meaning of these two terms.
Volume of any solid, liquid or gaseous substance refers to the amount of three-dimensional space that the substance occupies in the universe in order to actually exist. It is measured by the multiplying the length, the breadth and the height of the particular object and is expressed in terms of centimetre cube (cc) or metre cube (cm).
On the other hand, capacity of any substance is its ability to contain/hold or absorb a particular substance, in it i.e. it refers to the amount of any state of matter (solid, fluid or gas) that can accommodate itself into a container. The units of measurement of the capacity of a particular object are of millilitres, pounds, litres, gallons etc in different systems of measurements.
In spite of the fact that volume and capacity appear to be one and the same, the basic difference that lies between them is that where volume refers to that space which the object itself occupies, capacity refers to the amount of substance which the object can hold in itself. For an example, if a Drum has the volume of 500 cc. That means that the drum occupies a volumetric space of 500 cubic centimetres in the universe. On the other hand, if we say that the capacity of the same drum is 400 litres, it means that the drum can hold in itself any solid, liquid or gas having a maximum measurement of 400 litres.
Thus while measuring as well as referring to these terms, we have to be extra careful about the fact that we do not use one term in the [place where the other has to be used, because an interchange of the words can cause the meaning of the sentence to change completely and drastically.