Yeah,those are mylars,Mel.The mylar process uses mylar plastic and paint resulting in a heavier,thicker poster.No foil involved.Combination of paint and plastic makes for a very reflective poster,sometimes.Foil posters are extremely lightweight and thinner.You could breathe on it too hard and get a crinkle.
Foil is also a bit dull.It doesn't reflect as well as mylar.
I think out of the movie poster genre Superman and Dragonslayer would probably be my favs.Sadly,they didn't produce a lot of interesting foil,IMO.
My favorite foil,turns out, isn't a movie poster.Might have to drag it out cuz I can't find a pic.
Anthony