What is the difference between an outlier and an influential point?

An outlier is a data point that deviates significantly from the overall pattern of a dataset, often lying far from the other observations. An influential point, on the other hand, is a data point that, when removed, substantially alters the results of a statistical analysis, such as regression coefficients. While an outlier may not necessarily be influential, an influential point is typically an outlier that has a strong effect on the statistical model. Thus, all influential points can be outliers, but not all outliers are influential.