I have two linear regressions. The linear coefficients of both of them are very close to $1$. The first plot seems reasonable linear regression, while the second one is tricky since if the bottom left part or the top right part of the data (they are quite random) are fitted, we can not get a close-to-1 coefficient.
The question is how to distinguish the two regressions after I get their very similar regression coefficient values? Instead of by looking at the plots, a statistic is preferred to describe the difference of the two regressions. Any ideas?