What's the difference between MBP 2016 and 2017 Thunderbolt 3?

You gotta love the heightened level of complexity that simplifying things down to one connector has made things. Let's sort it out....

• USB-C is the connector type. It's the physical interface specification just as USB-A, USB-B, USB-Micro, USB-Mini are all physical connectors. It's not a USB port, nor is it a Thunderbolt port.

• USB 3.0/3.1 is the USB specification and port type. It sets the standard for how USB will communicate on your machine. It's backward compatible with USB 2.0, 1.1, and 1.0

• Thunderbolt 3 is the Thunderbolt specification that supplies DisplayPort, PCIe, USB 3.0 and power. It's backward compatible with Thunderbolt 2 and 1. Thunderbolt 3 utilizes the USB-C interface and Thunderbolt 1/2 utilize a mini DisplayPort interface connector.

• Daisy Chaining - Thunderbolt can be daisy chained, while DisplayPort cannot. Usually, displays are last in the Thunderbolt chain.

As for the Macs...

• MacBook Pros from 2016 onward have 2 or 4 Thunderbolt ports that utilize USB-C interfaces

• MacBooks have USB 3.1 ports with DisplayPort support that utilize USB-C interfaces.

So, when you are picking your adapter, you have to determine what port you have on your machine first. Then you pick the physical inteface type that works for you.

For example if you have a MacBook, you will have a USB port with DisplayPort support on a USB-C interface. This means you can use a USB to DVI/HDMI/DisplayPort adapter or you can use a USB-C DisplayPort to DisplayPort cable. What you can't use is a Thunderbolt cable/adapter

If you have a MacBook, you have a few more options because of the inclusion of Thunderbolt.

As for the iMac... Thunderbolt is Thunderbolt. It doesn't change from MacBook to iMac to PC. A Thunderbolt adapter for the MacBook Pro will work on an iMac because, after all, an iMac is a MacBook Pro in a different form factor.