Here's a 5 minute primer:
Electrical power is typically delivered as either AC (Alternating Current) or DC (Direct Current). Batteries use DC, while your household power is AC. A battery charger converts AC to DC, at the voltage required by the battery. EVs come with a battery charger in the car, allowing you to charge the car using household AC power.
Your typical "charger" is a Level 2 AC charging station. It delivers AC to the car and includes a communications protocol to tell the car how much power is OK to draw. The car uses its onboard battery charger to convert the AC to DC and charge its battery. Everybody uses the same communications protocol (J1772), but Tesla has a physically different plug from everyone else. The JDapter is just a mechanical adapter that lets you insert Tesla's plug into anyone else's car, for Level 2 AC charging. Since the protocol is the same, only a mechanical adapter is required.
Faster charging is called Level 3 DC charging and requires bypassing the limitations of the car's onboard battery charger. So the Level 3 station does the AC to DC conversion itself, and the supplied DC power is connected directly to the car battery to charge it. A communications protocol is required for the car to tell the Level 3 station the required voltage and allowable current to provide.
There are 3 communications protocols for Level 3 charging in use in North America: Chademo, SAE Combo, and Tesla Supercharger. They all have different plugs. Chademo (used by the Nissan LEAF) is a totally separate plug/receptacle from Level 2 AC charging; SAE Combo (like Bolt has) is a set of extra pins on the Level 2 plug/receptacle, and Tesla use the same physical plug for both Level 2 and Level 3. So Tesla's communications protocol includes having the car connect its charging receptacle either to the car's onboard battery charge (Level 2) or directly to the battery (Level 3).
The only interoperability of Level 3 charging currently possible is that Tesla has created an adapter that will let Tesla cars charge from Chademo stations. You attach the Chademo plug to the receptacle on the adapter, and the adapter's plug goes into the receptacle on the Tesla. This adapter is both mechanical and electronic, as it speaks "Chademo" to the Level 3 station and speaks "Tesla" to the car.