It has nothing to do with scale... It looks completely different.

It has different angles.... it is more obtuse....

And the neck is also thicker and wider on the executor than a normal SD

So far as scale goes in the shot i mentioned of falcon clamped on the back of the bridge.... It looks fairly consistant to me going by the rest of the shots that include the falcon and a star destroyer.... So the falcon is to big then? in all of the film?

Even if the scale is wrong in that shot it has more to do with keeping the audience in tune with what is actually happening rather than lose them in confusion or wether the falcon is exactly the right size.... the shot would have to be a pan out from falcon in terms of this