There is a little difference between population variance and sample variance, although the common thing with them is variance. And variance is all about how a single value depicts the distribution of individual values in a set around the mean. The major difference between population variance and sample variance is actually on how you calculate the two. There are different ways of calculating variance, which simply means you can calculate it from the population or from a sample.
The only difference between population variance and sample variance is that after you might have calculated the deviation from the mean, and you have squared it and summed it up. The sum is divided by the total number of the items being calculated. At this point, the denominator is calculated differently. For population variance, the sum is divided by the total number of the items, while in sample variance, the denominator is gotten by subtracting one from the total number of the items being calculated.