One of those links says "OverDrive - 486DX-2 with a slightly different pinout for use in 486SX systems."
I had a few Intel 486DX-2 OverDrive CPUs and they were completely interchangable with a true Intel 486DX-2 CPU. Not only could the hardware not see the difference between the OverDrive & non-OverDrive chip, but extensive benchmarking proved them to be identical in performance numbers.
However I never owned an "SX" machine so I couldn't do any testing there (that's IF there were any SX specific motherboards...I don't recall.)