One distributor has the built-in coil (hence no coil wire in cap), the other has external coil and igniter. The internal coil distributor is what I have seen on all 3a, 3ac, and 4ac engines (Tercel and corolla) in North America. The external coil I have seen on 22r engine used in the Celica and on the 4age engine (MR2, Corolla GTS, etc.). Unless this came from overseas, someone may have swapped out the distributor on your tercel. Where is your car from? Is it European? The Euro 3a engine in the Tercel has more power than the NA versions.
You should be able to swap back and forth if you adapt the wire harness, they should perform similarly but I suspect the one with the external coil might have a better advance curve since it came in the more high performance engines. Both are pretty reliable systems as far as i know.
My Tercel is an import from NYC to Manila, Philippines way back 1987 by the first owner, let me ask him if he changed the ignition system before.
Thanks anyways for the enlightenment... cheers..!!!
In the top picture, you are looking directly at the coil. The hum in the center between the two posts visible in this view is the wire that goes from the coil to the rotor.
