Have you ever used

   procedure Foo(constref Something: SomeType);

instead of

   procedure Foo(var Something: SomeType);

in Free Pascal? Both will pass the same stuff in memory (stack), but one has different semantics.

Similarly

   const NiceFeature = $01; NeatFeature = $02; GoodFeature = $04;
   var Features: Byte;

and

   {$packset 1}
   type Feature = (Nice, Neat, Good);
   var Features: set of Feature;

would be stored the same way in memory but again, different semantics with the compiler helping you in the second case to avoid logic bugs (e.g. setting Features to an invalid value).

These are cases where Free Pascal helps you from shooting yourself in the foot.