[FHFD]

The '41 has the wide "waterfall" hood emblem, along with two wide trim pieces on either side.
The '41 uses the Ford plate emblem on the rear of the hood near the cowl, and also on the dashboard (which is flat between the instrument cluster and glove box).

The '40 has the narrow hood emblem like the standard passenger car, and thin pieces of trim on either side.
The '40 uses the Ford script at the rear of the hood near the cowl, and also in the middle between the instrument cluster and glove box, which is recessed on the '40.

There are also differences on the hood latching mechanisms, and also on the front cross member depending on engine originally, the 4cyl used a deeper cross member then the V8.

The door glass is just glass on I believe the '40, where on the '41 it is framed in metal (I could have that backwards).

I believe that's it, if I've missed anything please post.