Sum, amount, number, aggregate, total, whole, quantity denote a result obtained by putting or taking together all in a given group or mass.
Sum denotes the result of simple addition, usually of figures, sometimes of particulars.
Amount denotes the result reached by combining all the sums or weights or measures that form a whole.
Number , with its strong suggestion of enumerating, is usually applied to a countable aggregate of persons or things and is clearly distinct from amount , which ordinarily applies to things in bulk or mass; thus, one may pick a large number of apples to make a large amount of applesauce.
Aggregate denotes the result reached by counting and considering together all the distinct individuals or particulars in a group or collection.
Total and whole suggest the completeness or inclusiveness of the result; total often further implies magnitude in the result, and whole , unity in what is summed up.
Quantity in general use is employed chiefly of things which are measured in bulk, even though they can be counted. In technical and scientific use quantity is not limited to an aggregate or bulk but may be used of anything that is measurable in extent, duration, volume, magnitude, intensity, or value.