Here are the answers.
A, B and C are all have pattern number 884. D and E have PN 975.
Except for A, can you tell which has which PN just by looking at the top? There really are no differences except for the pattern number.
The turn of the 20th Century was a time of innovation and change at Griswold for waffle irons. Experiments with a replacement for the finger hinge were happening. The finger hinge base did get an 884 PN.
Now for my assumptions.
I think the raised socket base started out with the 975 PN. It is shown in the patent for the acorn hinge. The acorn paddles got PNs 976 and 977. It would seem to make sense to give that base PN 975. It was more labor intensive (AKA expensive) to mold since a core would have been needed to put the bottom on the socket and keep the drip trough continuous.
I know what would become the ball or split socket base was starting to show up around the same time, but you find the early ones with an 884 PN. I'm sure they didn't worry about the reuse of the number since the finger hinge was essentially obsolete.
The ball socket base would have been less costly to make and would do the same job, so I suspect the swapped it into production giving it the 975 number. I had assumed the raised socket pattern would have just been discarded, but it seems that they gave it the 884 number, hopefully to just keep it from being used accidentally. I was unaware of this number on this base until recently.
Anyway, the real lesson here, even if you are not a waffle nerd, is to not assume you know what something is just by looking the top of it. Pick stuff up and open it to see what is inside, if applicable.
The photos are of the bottom of each base and have the same letters as the top views.
Just FWIW.
Tom