Count Scrofula is right, the bluesbird went thru many incarnations in its day.
As far as later period westerly bluesbirds vrs. blues 90, we used the same body and same neck specs ( blues 90 had dots and no binding), the other difference being what style of pickups the body was routed for.
If there appears to be a difference in neck thickness it would have to do with how much sanding Maria did that day. Also, the bluesbirds will tend to have a flatter fingerboard radius because of the additional sanding needed to level the block inlays.
As far as i know, corona bluesbirds were built out of leftover westerly stock.