The inlet & outlet are in different places & the top of the rad's a slightly different shape if memory serves me right, (it rarely does).
Loads of variances on tank shapes, even within the same car model ,depends on who the original manufacturers were. It what we used to sell to fit them;) Just like Mk1 /2 Escorts rads superceded all Cortinas , Anglias ,Corsairs ,Classics and Consul Capris they don't look the same but fit and do the job ...unless you are doing a 100 point resto .