Topre are decidedly not membrane keyboards.

They are rubber dome keyboards, but they don’t use a membrane to detect key-presses like standard rubber dome boards. They instead use a PCB in combination with a conical springs housed within the rubber domes. Key-presses are detected by measuring the change in capacitance caused by the compression of the spring.

I understand what you mean, though. Most of the time, “membrane” and “rubber dome” are used interchangeably to refer to cheap, mass produced keyboards. They are not necessarily related, though.

A keyboard can be one, and not the other, as with Topre, which is a Rubber Dome board, but not a membrane board. Then you have the legendary IBM Model M, which is not a rubber dome but is actually a membrane keyboard.