Not that the difference is clear in the photo, but... -- front side marker lights both have solid / hard plastic gaskets (bottom pair in pic). -- rear side marker lights both have compressible foam gaskets (top pair in pic). I can see how the rears need to seal to the point of being watertight and the fronts don't, but is what I have correct?
Yes, that is correct for the marker lights. I purchased some correct foam ones years ago. Can't find them anymore. Cars has the front ones.