How to interpret standard deviation of samples with different means?

Let be two samples collections A and B. Mean of the first is 5 and the second is 15. Standard deviation of the first is 2 and the second is 5.

Can we conclude something even though the two datasets have a different mean ?

Can we consider the ratio (standard deviation / mean) and conclude that A (0.4) is more widespread than B (0.33) ?

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As long as the distributions have the same shape, I guess it makes sense... – Arthur Sep 17 '12 at 14:36