1 ) correlation means relationship between two or more variables.

2) It is only a tool of ascertaining the degree of the relationship between two variables therefore we cannot say that one variable is the cause and other the effect.
3) There may be non sense correlation between two variables. Like correlation between income and weight.

4) It is independent of change of scale and origin.

5) It is confined only two the study of linear relationship between variables.

1) It means stepping back and returning to average value. It is the measure of average relationship between two or more variables in terms of the original units of data.

2) It indicates the cause and effect relationship between the variables as one variable is taken as dependent while other as independent.

3) There is no such thing like non sense regression.

 
4) It is independent of change of origin not scale.

5) It studies linear as well as non linear relationship between the variables.