They are different. The logo on the truck was the original intention. The Dolphins' brass never contemplated that the reverse C posture of the dolphin didn't work well on the helmet, violating common sense by running opposite of the natural curvature, leaving a motion sickness effect. Subsequently they have quietly tinkered with the angle of the logo itself, and the slant of the tail, as it applies to the helmet. I've seen at least three different versions. The version in the store may be the latest evolution, soon to replace anything that appeared during OTAs.
All you have to do is check the background of that picture with Griese, Marino and Tannehill to unveil the new uniforms. There's a helmet with the new logo between Griese and Tannehill. It's the truck version, with the severe upward slant and curved tail. That's certainly not what we are seeing today on the helmets.
I give them credit for partially salvaging a bad situation.