Both USB-C and Thunderbolt use the same USB-C connection. The difference is that a “generic” USB-C connection typically provides 10Gbps of bandwidth, and Thunderbolt provides 40Gbps, with a road to 120Gbps with 2024’s Thunderbolt 5.
Thunderbolt ports are becoming more common, so it’s possible that your laptop won’t have any “USB-C” ports; they’ll be Thunderbolt-enabled instead. (To tell the difference, consult your laptop’s manual or look for a small “lightning bolt” logo over the port itself. That’s usually a sign that it’s a Thunderbolt port.) A USB-C dongle and a Thunderbolt dock are similar, in that they both provide a number of additional ports.
There’s a key difference, though. The rule of thumb is that a USB-C dongle provides enough bandwidth for two 1080p displays at 60Hz, or a single 4K display at 30Hz. (Staring at any 30Hz display for a length of time can tire out your eyes, so I don’t recommend it.) A Thunderbolt dock, however, allows enough bandwidth to connect two 4K displays at 60Hz, plus all the peripherals you wish to attach. If you don’t need big, high-resolution displays, don’t buy a Thunderbolt dock and purchase a USB-C hub instead.
