You've kind of hit the point with the second half of your comment. Two populations are virtually never identical, so you don't need any statistics to answer th

You've kind of hit the point with the second half of your comment. Two populations are virtually never identical, so you don't need any statistics to answer the question. A more reasonable question is whether or not you have the statistical power (i.e. measurement precision) to see the difference, and whether the difference is big enough to matter.