There is only one difference between these two in time series. Forecasting pertains to out of sample observations, whereas prediction pertains to in sample observations. Predicted values (and by that I mean OLS predicted values) are calculated for observations in the sample used to estimate the regression. However, forecast is made for the some dates beyond the data used to estimate the regression, so the data on the actual value of the forecasted variable are not in the sample used to estimate the regression.
Residuals: Difference between the actual value of Y and its predicted value for observations in the sample.
Forecast error: Difference between future value of Y, which is not contained in the estimation sample, and the forecast of the future value.
Note : This was extracted from Introduction to Econometrics by Stock and Watson (p. 527)