The S17 and S17 Pro are identical, no hardware differences at all. They just select the hashboards that have the best efficiency for the Pro version, and the rest go to the non-pro.

The T17 used the identical chip, but put fewer of them in the same area (30 vs 48) with larger heatsinks so they could be run at higher frequencies at the expense of lower efficiency. Many T17s will run the same efficiency as an S17 when you drop the frequency and voltage. So with a bit of luck, your T17 might do 30TH or so at <40W/TH.

The S17+ was a redesign of the hashboard that used the newer version of the same chip, 1397AG vs the 1397AD for the S17/T17, and packed a bunch more chips on each hashboard. 65 chips for the S17+ hashboard vs 48 chips for the S17. I couldn't find any information on what the differences might be between AD and AG, but they seem to be interchangeable. I've replaced AD chips on S17s with AG chips and it worked fine. What I did see on the S17+ way more than the S17 was delamination of the copper plating on the top of the chip. The copper plating is what the heatsinks are soldered to, and when it delaminates the heatsink can come off with the copper with little force. If you ship a S17+ that has chips with copper delamination, it will likely show up at its destination with a bunch of heatsinks detached from their chips and jingling around loose. Which is how every one of the S17+s I've looked at arrived. Not sure if the delamination issue was more from the new chip version, or just from the higher possibility of excess heat caused by packing more chips into the same area. Could also be that the temperature got too high for too long during board assembly.

The T17+ was the same idea as the T17. I haven't looked at one in person but I'd guess they have the same delamination issues as the S17+.

The S17e was a completely different beast, different chip (1396), and an insane number of them on a single board, 135 chips per board. I took a look at a dead one for my host once and after seeing it in person I just sent it back to him. Looked like a complete nightmare to work on. But that was the only one I saw, and I didn't even take a chip off, so I don't really have any thoughts on them other than I don't want to mess with them.