How can I tell when I can use Mini-DisplayPort and Thunderbolt 1 or 2 interchangeably?
Although Mini-DisplayPort and Thunderbolt versions 1 and 2 share the same 20-pin connector, care must be taken on how the standards are adapted or utilized.
Thunderbolt can configure itself to have Mini-DisplayPort signals, but Mini-DisplayPort does not contain Thunderbolt signals. Therefore, a Thunderbolt source can connect to Thunderbolt and Mini-DisplayPort devices or displays. A Mini-DisplayPort source cannot connect to Thunderbolt monitors or devices (for example, Apple Cinema Display).
Note: When you connect a Thunderbolt source to a Mini-DisplayPort display, you must use a Mini-DisplayPort cable.