pre and post cat O2 sensors

Anyone know if there is any differance between the pre and post cat O2 sensors?

I know they have differant part numbers and i think the cable length is differant but is there any other differance?

Basically can i take the sensor out the post cat and use it in pre cat?

its in my 97 4.0L

Any ideas or suggestions?
thanks

the connectors on the two are different