taurus o2 sensor differences

I have a question about the differences between Taurus O2 sensors. In this case, 1997 Taurus 3.0l OHV. It has two O2 forward and one post cat.
My post cat sensor got broke and stuck.
I unstuck it, and had a spare O2 from a core. These O2 were from the front.
It turns out, the post cat o2 sensor is keyed different in the 4 pin connector. I files off the keys and stuck it in for now.
So, what is the difference between the pre cat and post cat sensors electrically? I did notice a heat resistant cover on the wire of the post cat. Is that really the only difference?
bob
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The fact it's keyed differently is a major clue it's not the same. There must be some reason it's covered. It may also respond differently than the front versions. Try and replace it with the correct version as soon as possible.
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