The difference between maximum and minimum is called the range of the variable. Finally, we have the standard deviation . The standard deviation is a fairly technical measure, difficult to explain to a non-statistical audience. For now, we just keep in mind that a smaller value for the standard deviation means that the individual values are closer clustered around the mean. I don't think I can do a better job.
Box plots are particularly useful when making comparisons.
When you have just one variable, a histogram is usually the better choice.