Sometimes performing Regression will come up with different values than the simple linear equation returned by Relate.  This happens because they use different methods of regression, Regression uses M-estimation by default and Relate uses OLS (Ordinay Least Squares).

The regression method used in Regression can be seen by clicking the little cog like button on the right hand side of the card header, seen below: 

Which will open the following dialog:

Choosing OLS for Regression will give results identical to a Relate of two numbers.