Difference between variance-covariance and correlation matrix?

Variance/Covariance To start off, the sample variance formula is: [s^2 = \frac{\sum_{i=1}^{n}(x_i - \overline{x})^2} {n - 1 }] First of all, (x - \overline{x}) is a deviation score (deviation from what? deviation from the mean). Summing the deviations will just get us zero so the deviations are squared and then added together. The numerator of this formula is then called the sum of squared deviations which is literally what it is.