What is the different between 41AB150-2 and 41AC150-2?

The numbers are definitely different. The difference between OBD I and OBD II are like the differences between a Windows 3.0 operating system and a Windows 10 machine. Even though they both do the same thing, there are vast differences.

I would expect such a swap to be extremely difficult, these engines are quite different, have different mounts, different clutch-plates/transmission connections, different plumbing, and different "brain" requirements. While it might be possible, it would likely be far less expensive to fix whatever is wrong than try such a graft.

check your vehicle pushing and see that the ring is inside the spring is not broken or worn out... try replacing it

You need to give more information. The DTC's (Diagnostic Trouble Codes) are different for the different models and years of vehicles. Cars are different than trucks, Diesel trucks are different than Gasoline Trucks. 1995 and older are different than 1996 and newer.
What make, year and model is it?

Your computer is wired for different settings from the different ign module. Also the reference wiring for eng sensors are different. Basically the eng is same but different electronic controls.

tire pressure should be on side wall tire pressure is different for different tires ,different car,different driving conditions somewhere between 35 and 50 psi for road 20 to 30 for sand and mud see tire dealer for more info

If the ECUs have different part numbers, they are NOT the same...The thing will most likely might hook up to your electrical connector and mount the same, but they are different computers for different vehicles that most likely are equipped with different features. i.e. different engines, different engine controls, different emissions controls, one may have cruise control and the other not or they may be for the same engine with a different transmission, etc..

I am curious however as to how this all came about. The ECU failed from attempting to start the new engine??? What was wrong with your engine that it needed to be replaced and how did the ECU manage to fail because of an engine replacement? Was the other engine running when it was determined that it needed replacing? ECUs don't fail very often...I'd like to know what the problem is.

W is a flex fuel engine and some the electronics on them are different for use of E-85 fuel. Different fuel pump,fuel regulator and injectors.

you have 604 the differabces will be in the bell housing. 4 cyl hanve differant bells than v-6 and even differant v-6 will have differant bells. then the early 604 has differant locations for electrical connecters and later modals have differan style mounts. and then some also take differant torque converters. just match year make and model to the one you have or better yet take it a reputable tranny shop and have yours rebuilt. itll cost you but it may be worth it.

the all wheel drive is just a bolt on unit but i think its the pass axle thats differant.

physical difference and electronics