We have quite a few documents that answer your questions:
What is the difference between the Matrix, Multiplexer and General Porpuse modules?
Why are some SCXI and some PXI is there and advantage to one over the other?
Some modules can be configured as multiplexer or matrix by using a very flexible design and placing judiciously relays on the PCB.
Whats the difference between 145 Cycles/s, 25,000 Channels/s, 2000 Crosspoints/s, 10 ms, which are all listed under switch speed on the same page?
The difference comes from the type of switch modules you are referring to. Cycles/s, Channels/s, Crosspoints/s are for genral purpose, multiplexer, and matrix respectivelly that can be used in scanning mode.
ms indicates speed on switch mdodules that do ot suipport scanning.
Guy Ferraro
Switch Product Suppport Engineer
NI USA