ANCOVA or Analysis of Covariance is a statistical tool that depends on linear regression, which means the dependent variable must be linear to the independent variable. This statistical method is used to determine the extent of the variability of one variable as a result of the variability of others. Regression, on the other hand, is a statistical method used to determine how one or more independent variables are associated with a dependent variable. It is basically the relationship between one dependent variable and one or more independent variables.
It helps to determine if the values of a dependent variable will be affected due to any changes occurring to any of the independent variables. This statistical method is used in many variants, such as logistic regression, nonparametric regression, simple linear regression, stepwise regression, nonlinear regression, etc. In regression, one independent variable can be used to determine or predict the values of a dependent variable. At times, more independent variables can be used to determine or predict the values of a dependent variable.