Bob O’Donnell, writing for Tech.pinions:

The crux of the problem is that not all USB Type-C connectors support all of these different capabilities and, with one important exception, it’s almost impossible for an average person to figure out what a given USB Type-C equipped device supports without doing a good deal of research.

The key exception is for Thunderbolt 3.0, a technology originally developed by Intel. It’s a different interface standard than USB 3.1, but uses the same USB Type-C connectors. Thunderbolt 3.0 connectors (which, by the way, are different than previous versions of Thunderbolt—versions 1 and 2 used the same connectors as the mini-DisplayPort video standard) are marked by a lightning bolt next to the connector, making them easy for almost anyone to identify. To be clear however, they aren’t the same as the somewhat similarly shaped Lightning connectors used by Apple (which, ironically, don’t have a lightning bolt next to them). Confused? You’re not alone.

This is a bit of a mess. Critical that manufacturers/resellers publish compatibility specs with each new device so you know what you can plug in where.