Differences between the obd1 and obd2 engine harness?

[Heli-Mech]

I have a few questions for some of the wiring experts. I am trying to figure out what the main differences between the obd1 and obd2 engine harness's and bulk head harness's.
-Are the main connectors between the bullhead and engine the same from obd1 to obd2.
-is it possible to run an obd1 intake manifold and harness with a obd2 bulkhead harness and ecu? (aside from a few missing sensors, possibly emissions junk)
-What are the primary differences (aside from the ecu and tcu interface) from obd1 and obd2.

Cheers,
Ian