Close-up of the TK helmet. Note the Side vents are actual vents, the teardrops are separate plates with grooves cut into them (can't tell if it's metal or just a reflection on glossy plastic) and the mouthpiece seems to be individual tubes, or at least separated into sections as you can see a gap between them.
http://smg.photobucket.com/user/Netliquid/media/Rogue One Stormtrooper Helmet.jpg.html
http://img.photobucket.com/albums/v383/Netliquid/Rogue One Stormtrooper Helmet.jpg
Hope Jez doesn't mind me borrowing one of his pics.
I've got the Riddell stormtrooper mini helmet, and it is an idealized ROTJ , symmetrical bucket. It's got the more detailed ear cap covers and the tube stripes are actual vents/ openings in the helmet.

