What is the best way to illustrate variability?

If you measure all of the trees in a population, say at the BFEC, the mean you calculate is the "true" mean of that population, and the variability represents biological differences in the trees. Now, if you wanted to extrapolate to all one-year old Pinus strobus in the world, the calculated mean is unlikely to be the "true" mean. For this reason, when means are presented, they are generally presented +/- some measure of variability along with the sample.

How do the above measures of variability compare?