This has to be simple if you know what you're doing?

#1
I have two data sets with very different magnitudes. The first data set ranges from 2000 to 40000. The second data set ranges from 20 to 500. I suspect the first data set has greater variability than the second set. What statistic could I use to compare the variation between the two data sets? Comparing SE or SD seems inappropriate.
 
#2
Why do you think comparing the SDs is inappropriate?

In theory you could transform the first dataset by making y=x/100, say, to give you a similar range to the second set, but this really depends on what the data are measures of and whether they are still comparable.