the modelj as we know (oldstyle) has the primer button on the side and the reed plate with the rubber square
the modelj new style has the primer button removed, i cant say about the inside of the new one but i'll make an assumption that it is the same as the oldstyle reed plate.

As for the cobra there is a valve plunger in the place where the reed plate is and it has a rubber button on the end of the plunger that goes into a hole. So basically the diaphram moves the plunger in and out of the hole.

there may be some other small differences but as for what i could see that was the biggest difference between the two.