I agree, not much of a difference. Most people may not care and would never notice but some people might like to know.

I am not one of those "if it was that way on my car it had to be that way on every car" kind of guys. I am sure that they didn't spec out the dimensions of the rivets to ±0.001 so I am guessing there are variations out there. Even the two original ones on mine were a little different.

In my case I was repairing a rust spot on the dash and not respraying the vin tag so the smaller head on the ECS rivet stuck out like a sore thumb with the wear marks from the original rivets being visible.