The Grey ones were first, commonly called "push start" because they didn't really need the engine computer at all to start and run spark
They had timing and dwell control but no "load advance"(vacuum advance), that still needed to come from computer on SPOUT wire
You can drive vehicle without computer(assuming carburetor), would just stumble a bit on acceleration because of no load advance, but would run fine once at steady RPM
The Black ones, used/needed CCD, computer controlled dwell, and were not used in Rangers at all, but were used in 1990's Fords until those models went to distributorless spark systems, it allowed for better emissions which was needed in later years
Engine may start but would run poorly without computer(assuming carburetor)
Easy to read article here:
https://usermanual.wiki/m/63e50a12c012daab6e1780f7b115e15c0528e95750a78dc5372bc7b58f70979c.pdf
Dwell is the time allowed for the Coil to "RECHARGE"
An ignition coil works by having 12v when key is on
Then, in this case, TFI module grounds it to build up a12v magnetic field in its Primary coil
When TFI ungrounds it the magnetic field collapses and that sends out a high voltage spark from the Secondary coil
The longer the coil is grounded the higher the Secondary voltage will be, up to a point, lol
The Dwell is the length of time the coil is grounded between sparking, length of time it "recharges" secondary coil